Which of the following is the main top...

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation. Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things. At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit, and if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years. This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents. Radiation can hurt us. We must know the truth.According to the passage, the danger of nuclear power lies in______.

A．nuclear mystery
B．radiation detection
C．radiation level
D．nuclear radiation

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation. Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things. At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit, and if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years. This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents. Radiation can hurt us. We must know the truth.Radiation can cause serious consequences even at the lowest level______.

A．when it kills few cells
B．if it damages few cells
C．though the damaged cells can repair themselves
D．unless the damaged cells can reproduce themselves

单项选择题

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation. Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things. At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit, and if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years. This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents. Radiation can hurt us. We must know the truth.The word "significant" in Paragraph 3 most probably means______.

A．remarkable
B．meaningful
C．fatal
D．harmful

单项选择题

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation. Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things. At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit, and if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years. This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents. Radiation can hurt us. We must know the truth.Radiation can hurt us in the way that it can______.

A．kill large numbers of cells in main organs so as to cause death immediately
B．damage cells which may grow into cancer years later
C．affect the healthy grow of our offspring
D．all of the above

单项选择题

In some ways, the United States has made spectacular progress. Fires no longer destroy 18,000 buildings as they did in the Great Chicago Fire of 1871, or kill half a town of 2,400 people, as they did the same night in Peshtigo, Wisconsin. Other than the Beverly Hill Supper Club fire in Kentucky in 1977, it has been four decades since more than 100 Americans died in a fire. But even with such successes, the United States still has one of the worst fire death rates in the world. Safety experts say the problem is neither money nor technology, but the indifference of a country that just will not take fires seriously enough. American fire departments are some of the world’s fastest and best-equipped. They have to be. The United States has twice Japan’s population, and 40 times as many as fires. It spends far less on preventing fires than on fighting them. And American fire-safety lessons are aimed almost entirely at children, who die in disproportionately large numbers in fires but who, contrary to popular myth, start very few of then. Experts say the fatal error is an attitude that fires are not really anyone’s fault. That is not so in other countries, where both public education and the law treat fires as either a personal failing or a crime. Japan has many wood houses; of the estimated 48 fires in world history that burned more than 10,000 buildings, Japan has had 27. Penalties for causing a severe fire by negligence can be as high as life imprisonment. In the United States, most education dollars are spent in elementary schools. But the lessons are aimed at too limited an audience; just 9 percent of all fire deaths are caused by children playing with matches. The United States continues to rely more on technology than laws or social pressure. There are some smoke detectors in 85 percent of all homes. Some local building codes now require home sprinklers. New heaters and irons shut themselves off if they are tipped.The reason why so many Americans die in fires is that______.

A．they took no interest in new technology
B．they did not attach great importance to preventing fires
C．they showed indifference to fighting fires
D．they did not spend enough money on fire facilities

单项选择题

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation. Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things. At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit, and if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years. This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents. Radiation can hurt us. We must know the truth.Which of the following can be best inferred from the passage

A．The importance of protection from radiation cannot be over-emphasized.
B．The mystery about radiation remains unsolved.
C．Cancer is mainly caused by radiation.
D．Radiation can hurt those who are not aware of its danger.

单项选择题

In some ways, the United States has made spectacular progress. Fires no longer destroy 18,000 buildings as they did in the Great Chicago Fire of 1871, or kill half a town of 2,400 people, as they did the same night in Peshtigo, Wisconsin. Other than the Beverly Hill Supper Club fire in Kentucky in 1977, it has been four decades since more than 100 Americans died in a fire. But even with such successes, the United States still has one of the worst fire death rates in the world. Safety experts say the problem is neither money nor technology, but the indifference of a country that just will not take fires seriously enough. American fire departments are some of the world’s fastest and best-equipped. They have to be. The United States has twice Japan’s population, and 40 times as many as fires. It spends far less on preventing fires than on fighting them. And American fire-safety lessons are aimed almost entirely at children, who die in disproportionately large numbers in fires but who, contrary to popular myth, start very few of then. Experts say the fatal error is an attitude that fires are not really anyone’s fault. That is not so in other countries, where both public education and the law treat fires as either a personal failing or a crime. Japan has many wood houses; of the estimated 48 fires in world history that burned more than 10,000 buildings, Japan has had 27. Penalties for causing a severe fire by negligence can be as high as life imprisonment. In the United States, most education dollars are spent in elementary schools. But the lessons are aimed at too limited an audience; just 9 percent of all fire deaths are caused by children playing with matches. The United States continues to rely more on technology than laws or social pressure. There are some smoke detectors in 85 percent of all homes. Some local building codes now require home sprinklers. New heaters and irons shut themselves off if they are tipped.Although the fire death rate has declined, the United States______.

A．still has the worst fire death rate in the world
B．is still alert to the fire problem
C．is still training a large number of safety experts
D．is still confronted with the serious fire problem

单项选择题

There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO ₂ and further boosting global warming. There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase. Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels. Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO ₂ yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming."Feedback mechanisms" in Paragraph 1 most probably refers to______.

A．how plants and animals adapt to hidden factors
B．how plants and animals interact with the changing climate
C．how climate changes
D．how climate zones shift

单项选择题

In some ways, the United States has made spectacular progress. Fires no longer destroy 18,000 buildings as they did in the Great Chicago Fire of 1871, or kill half a town of 2,400 people, as they did the same night in Peshtigo, Wisconsin. Other than the Beverly Hill Supper Club fire in Kentucky in 1977, it has been four decades since more than 100 Americans died in a fire. But even with such successes, the United States still has one of the worst fire death rates in the world. Safety experts say the problem is neither money nor technology, but the indifference of a country that just will not take fires seriously enough. American fire departments are some of the world’s fastest and best-equipped. They have to be. The United States has twice Japan’s population, and 40 times as many as fires. It spends far less on preventing fires than on fighting them. And American fire-safety lessons are aimed almost entirely at children, who die in disproportionately large numbers in fires but who, contrary to popular myth, start very few of then. Experts say the fatal error is an attitude that fires are not really anyone’s fault. That is not so in other countries, where both public education and the law treat fires as either a personal failing or a crime. Japan has many wood houses; of the estimated 48 fires in world history that burned more than 10,000 buildings, Japan has had 27. Penalties for causing a severe fire by negligence can be as high as life imprisonment. In the United States, most education dollars are spent in elementary schools. But the lessons are aimed at too limited an audience; just 9 percent of all fire deaths are caused by children playing with matches. The United States continues to rely more on technology than laws or social pressure. There are some smoke detectors in 85 percent of all homes. Some local building codes now require home sprinklers. New heaters and irons shut themselves off if they are tipped.It can be inferred from the passage that______.

A．fire safety lessons should be aimed at American adults
B．American children have not received enough education of fire safety lesson
C．Japan is better equipped with fire facilities than the United States
D．America’s large population accounts for high fire frequency

单项选择题

There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO ₂ and further boosting global warming. There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase. Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels. Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO ₂ yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming.James Hansen predicts that the shift of climate zones will be accompanied by______.

A．the cutting of many trees
B．desirable environmental changes
C．successful migration of species
D．unsuccessful migration of trees

单项选择题

In some ways, the United States has made spectacular progress. Fires no longer destroy 18,000 buildings as they did in the Great Chicago Fire of 1871, or kill half a town of 2,400 people, as they did the same night in Peshtigo, Wisconsin. Other than the Beverly Hill Supper Club fire in Kentucky in 1977, it has been four decades since more than 100 Americans died in a fire. But even with such successes, the United States still has one of the worst fire death rates in the world. Safety experts say the problem is neither money nor technology, but the indifference of a country that just will not take fires seriously enough. American fire departments are some of the world’s fastest and best-equipped. They have to be. The United States has twice Japan’s population, and 40 times as many as fires. It spends far less on preventing fires than on fighting them. And American fire-safety lessons are aimed almost entirely at children, who die in disproportionately large numbers in fires but who, contrary to popular myth, start very few of then. Experts say the fatal error is an attitude that fires are not really anyone’s fault. That is not so in other countries, where both public education and the law treat fires as either a personal failing or a crime. Japan has many wood houses; of the estimated 48 fires in world history that burned more than 10,000 buildings, Japan has had 27. Penalties for causing a severe fire by negligence can be as high as life imprisonment. In the United States, most education dollars are spent in elementary schools. But the lessons are aimed at too limited an audience; just 9 percent of all fire deaths are caused by children playing with matches. The United States continues to rely more on technology than laws or social pressure. There are some smoke detectors in 85 percent of all homes. Some local building codes now require home sprinklers. New heaters and irons shut themselves off if they are tipped.In what aspects should the United States learn from Japan

A．Architecture and building material.
B．Education and technology.
C．Laws and attitude.
D．All of the above.

单项选择题

There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO ₂ and further boosting global warming. There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase. Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels. Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO ₂ yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming.We can learn from the passage that______.

A．some feedback mechanisms may slow down global warming
B．the basic facts of global warming are unknown
C．developing countries benefit from cheap fossil fuels
D．developed countries have decided to reduce their energy consumption

单项选择题

In some ways, the United States has made spectacular progress. Fires no longer destroy 18,000 buildings as they did in the Great Chicago Fire of 1871, or kill half a town of 2,400 people, as they did the same night in Peshtigo, Wisconsin. Other than the Beverly Hill Supper Club fire in Kentucky in 1977, it has been four decades since more than 100 Americans died in a fire. But even with such successes, the United States still has one of the worst fire death rates in the world. Safety experts say the problem is neither money nor technology, but the indifference of a country that just will not take fires seriously enough. American fire departments are some of the world’s fastest and best-equipped. They have to be. The United States has twice Japan’s population, and 40 times as many as fires. It spends far less on preventing fires than on fighting them. And American fire-safety lessons are aimed almost entirely at children, who die in disproportionately large numbers in fires but who, contrary to popular myth, start very few of then. Experts say the fatal error is an attitude that fires are not really anyone’s fault. That is not so in other countries, where both public education and the law treat fires as either a personal failing or a crime. Japan has many wood houses; of the estimated 48 fires in world history that burned more than 10,000 buildings, Japan has had 27. Penalties for causing a severe fire by negligence can be as high as life imprisonment. In the United States, most education dollars are spent in elementary schools. But the lessons are aimed at too limited an audience; just 9 percent of all fire deaths are caused by children playing with matches. The United States continues to rely more on technology than laws or social pressure. There are some smoke detectors in 85 percent of all homes. Some local building codes now require home sprinklers. New heaters and irons shut themselves off if they are tipped.To narrow the gap between the fire death rate in the United States and that in other countries, the author suggests______.

A．developing new technology
B．counting more on laws and social pressure
C．placing a fire extinguisher in every family
D．reinforcing the safeness of household appliances

单项选择题

There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO ₂ and further boosting global warming. There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase. Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels. Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO ₂ yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming.It can be inferred from the passage that______.

A．the developing world has decided to increase its energy consumption
B．a third-world citizen adds less than a ton of CO ₂ yearly to the atmosphere
C．the world climate would soon gain its balance if we stopped greenhouse-gas emissions
D．future prosperity of the world is dependent on cheap fossil fuels

单项选择题

There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO ₂ and further boosting global warming. There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase. Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels. Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO ₂ yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming.Which of the following is the main topic of the passage

A．Material Progress and Energy Consumption.
B．Prosperity and Cheap Fossil Fuels.
C．Impact of Global Warming on Climate.
D．Plants and Animals in the Changing Climate.

单项选择题

Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of the learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning-disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’s electrical activity and made a map of the electrical’ signals. Frank Duffy experimented with this technique at Children’s Hospital Medical Center in Boston. Doctor Duffy found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Duffy said his research is evidence that reading disabilities involve damage to a wide area of the brain, not just the left side.Scientists found that the brain cells of a learning-disabled person differ from those of a normal person in______.

A．structure and function
B．color and function
C．size and arrangement
D．color and arrangement

单项选择题

Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of the learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning-disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’s electrical activity and made a map of the electrical’ signals. Frank Duffy experimented with this technique at Children’s Hospital Medical Center in Boston. Doctor Duffy found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Duffy said his research is evidence that reading disabilities involve damage to a wide area of the brain, not just the left side.Which of the following is NOT mentioned in the passage

A．Learning disabilities may result from the unknown area of the brain.
B．Learning disabilities may result from damage to a wide area of the brain.
C．Learning disabilities may result from abnormal organization of brain cells.
D．Learning disabilities may result from problems in the left side of the brain.

单项选择题

Visual impairment(视觉障碍)carries with it a reduced or restricted ability to travel through one’s physical and social environment until adequate orientation(定方位)and mobility(移动)skills have been established. Because observational skills are more limited, self-control within the immediate surroundings is limited. The visually impaired person is less able to anticipate hazardous situations or obstacles to avoid. Orientation refers to the mental map one has of one’s surrounding and to the relationship between self and that environment. The mental map is best generated by moving through the environment and piecing together relationships, object by object, in an organized approach. With little or no visual feedback to reinforce this mental map, a visually impaired person must rely on memory for key landmarks and other clues. Landmarks and clues enable visually impaired persons to affirm their position in space. Mobility, on the other hand, is the ability to travel safely and efficiently from one point to another within one’s physical and social environment. Good orientation skills are necessary to good mobility skills. Once visually impaired students learn to travel safely as pedestrians(fA)they also need to learn to use public transportation to become as independent as possible. To meet the expanding needs and demands of the visually impaired person, there is a sequence of instruction that begins during the preschool years and may continue after high school. Many visually impaired children lack adequate concepts regarding time and space or objects and events in their environment. During the early years much attention is focused on the development of some fundamental concepts, such as inside or outside, in front of or behind, fast or slow movement of traffic, the variety or intersections, elevators or escalators, and so forth. These concepts are essential to safe, efficient travel through familiar and unfamiliar settings, first within buildings, then in residential neighborhoods, and finally in business communities.How can we increase the visually impaired person’s ability to travel through his physical and social environment

A．By helping him develop adequate orientation and mobility skills.
B．By teaching him to learn observational skills.
C．By warning him of hazardous situations or obstacles.
D．By improving his visual ability.

单项选择题

Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of the learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning-disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’s electrical activity and made a map of the electrical’ signals. Frank Duffy experimented with this technique at Children’s Hospital Medical Center in Boston. Doctor Duffy found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Duffy said his research is evidence that reading disabilities involve damage to a wide area of the brain, not just the left side.All of the following statements are true EXCEPT that______.

A．many factors account for learning disorder
B．a learning-disabled person shows no outward signs
C．reading disabilities are common problem that affects 10 percent of the population
D．the brain activity of learning-disabled children is different from that of normal children

单项选择题

Visual impairment(视觉障碍)carries with it a reduced or restricted ability to travel through one’s physical and social environment until adequate orientation(定方位)and mobility(移动)skills have been established. Because observational skills are more limited, self-control within the immediate surroundings is limited. The visually impaired person is less able to anticipate hazardous situations or obstacles to avoid. Orientation refers to the mental map one has of one’s surrounding and to the relationship between self and that environment. The mental map is best generated by moving through the environment and piecing together relationships, object by object, in an organized approach. With little or no visual feedback to reinforce this mental map, a visually impaired person must rely on memory for key landmarks and other clues. Landmarks and clues enable visually impaired persons to affirm their position in space. Mobility, on the other hand, is the ability to travel safely and efficiently from one point to another within one’s physical and social environment. Good orientation skills are necessary to good mobility skills. Once visually impaired students learn to travel safely as pedestrians(fA)they also need to learn to use public transportation to become as independent as possible. To meet the expanding needs and demands of the visually impaired person, there is a sequence of instruction that begins during the preschool years and may continue after high school. Many visually impaired children lack adequate concepts regarding time and space or objects and events in their environment. During the early years much attention is focused on the development of some fundamental concepts, such as inside or outside, in front of or behind, fast or slow movement of traffic, the variety or intersections, elevators or escalators, and so forth. These concepts are essential to safe, efficient travel through familiar and unfamiliar settings, first within buildings, then in residential neighborhoods, and finally in business communities.The visually impaired person’s position in space______.

A．is not determined by memory but by physical landmarks and clues
B．is located in relation to other items in his mental map
C．enables him to construct the mental map
D．reinforces the mental map of his surroundings

单项选择题

Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of the learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning-disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’s electrical activity and made a map of the electrical’ signals. Frank Duffy experimented with this technique at Children’s Hospital Medical Center in Boston. Doctor Duffy found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Duffy said his research is evidence that reading disabilities involve damage to a wide area of the brain, not just the left side.Doctor Duffy believed that______.

A．he found the exact cause of learning disabilities
B．the problem of learning disabilities was not limited to the left side of the brain
C．the problem of learning disabilities resulted from the left side of the brain
D．the problem of learning disabilities did not lie in the left side of the brain

单项选择题

Visual impairment(视觉障碍)carries with it a reduced or restricted ability to travel through one’s physical and social environment until adequate orientation(定方位)and mobility(移动)skills have been established. Because observational skills are more limited, self-control within the immediate surroundings is limited. The visually impaired person is less able to anticipate hazardous situations or obstacles to avoid. Orientation refers to the mental map one has of one’s surrounding and to the relationship between self and that environment. The mental map is best generated by moving through the environment and piecing together relationships, object by object, in an organized approach. With little or no visual feedback to reinforce this mental map, a visually impaired person must rely on memory for key landmarks and other clues. Landmarks and clues enable visually impaired persons to affirm their position in space. Mobility, on the other hand, is the ability to travel safely and efficiently from one point to another within one’s physical and social environment. Good orientation skills are necessary to good mobility skills. Once visually impaired students learn to travel safely as pedestrians(fA)they also need to learn to use public transportation to become as independent as possible. To meet the expanding needs and demands of the visually impaired person, there is a sequence of instruction that begins during the preschool years and may continue after high school. Many visually impaired children lack adequate concepts regarding time and space or objects and events in their environment. During the early years much attention is focused on the development of some fundamental concepts, such as inside or outside, in front of or behind, fast or slow movement of traffic, the variety or intersections, elevators or escalators, and so forth. These concepts are essential to safe, efficient travel through familiar and unfamiliar settings, first within buildings, then in residential neighborhoods, and finally in business communities.Mobility skill which the visually impaired person is learning refers to the ability______.

A．to travel as a dependent tourist
B．to travel as a pedestrian and a passenger
C．to travel as a pedestrian with a company
D．to travel within the safe physical and social environment

单项选择题

Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of the learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning-disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’s electrical activity and made a map of the electrical’ signals. Frank Duffy experimented with this technique at Children’s Hospital Medical Center in Boston. Doctor Duffy found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Duffy said his research is evidence that reading disabilities involve damage to a wide area of the brain, not just the left side.According to the passage we can conclude that further researches should be made______.

A．to investigate possible influences on brain development and organization
B．to study how children learn to read and write, and use numbers
C．to help learning-disabled children to develop their intelligence
D．to explore how the left side of the brain functions in language learning

单项选择题

Visual impairment(视觉障碍)carries with it a reduced or restricted ability to travel through one’s physical and social environment until adequate orientation(定方位)and mobility(移动)skills have been established. Because observational skills are more limited, self-control within the immediate surroundings is limited. The visually impaired person is less able to anticipate hazardous situations or obstacles to avoid. Orientation refers to the mental map one has of one’s surrounding and to the relationship between self and that environment. The mental map is best generated by moving through the environment and piecing together relationships, object by object, in an organized approach. With little or no visual feedback to reinforce this mental map, a visually impaired person must rely on memory for key landmarks and other clues. Landmarks and clues enable visually impaired persons to affirm their position in space. Mobility, on the other hand, is the ability to travel safely and efficiently from one point to another within one’s physical and social environment. Good orientation skills are necessary to good mobility skills. Once visually impaired students learn to travel safely as pedestrians(fA)they also need to learn to use public transportation to become as independent as possible. To meet the expanding needs and demands of the visually impaired person, there is a sequence of instruction that begins during the preschool years and may continue after high school. Many visually impaired children lack adequate concepts regarding time and space or objects and events in their environment. During the early years much attention is focused on the development of some fundamental concepts, such as inside or outside, in front of or behind, fast or slow movement of traffic, the variety or intersections, elevators or escalators, and so forth. These concepts are essential to safe, efficient travel through familiar and unfamiliar settings, first within buildings, then in residential neighborhoods, and finally in business communities.In the passage, the author insists that______.

A．visually, impaired children go to school for survival
B．the needs and demands of visually impair children expand
C．visually impaired children acquire the fundamental concepts for safe mobility
D．preschool children receive the instruction in the concepts of time and space or objects and events

单项选择题

Visual impairment(视觉障碍)carries with it a reduced or restricted ability to travel through one’s physical and social environment until adequate orientation(定方位)and mobility(移动)skills have been established. Because observational skills are more limited, self-control within the immediate surroundings is limited. The visually impaired person is less able to anticipate hazardous situations or obstacles to avoid. Orientation refers to the mental map one has of one’s surrounding and to the relationship between self and that environment. The mental map is best generated by moving through the environment and piecing together relationships, object by object, in an organized approach. With little or no visual feedback to reinforce this mental map, a visually impaired person must rely on memory for key landmarks and other clues. Landmarks and clues enable visually impaired persons to affirm their position in space. Mobility, on the other hand, is the ability to travel safely and efficiently from one point to another within one’s physical and social environment. Good orientation skills are necessary to good mobility skills. Once visually impaired students learn to travel safely as pedestrians(fA)they also need to learn to use public transportation to become as independent as possible. To meet the expanding needs and demands of the visually impaired person, there is a sequence of instruction that begins during the preschool years and may continue after high school. Many visually impaired children lack adequate concepts regarding time and space or objects and events in their environment. During the early years much attention is focused on the development of some fundamental concepts, such as inside or outside, in front of or behind, fast or slow movement of traffic, the variety or intersections, elevators or escalators, and so forth. These concepts are essential to safe, efficient travel through familiar and unfamiliar settings, first within buildings, then in residential neighborhoods, and finally in business communities.What is the author mainly talking about in the passage

A．Visual impairment and memory.
B．The visually impaired person’s physical and social environment.
C．Mental development of the visually impaired person.
D．Orientation and mobility of the visually impaired person.

单项选择题

Our bodies are wonderfully skillful at maintaining balance. When the temperature jumps, we sweat to cool down. When our blood pressure falls, our hearts pound to compensate. As it turns out, though, our natural state is not a steady one. Researchers are finding that everything from blood pressure to brain function varies rhythmically with the cycles of sun, moon and seasons. And their insights are yielding new strategies for keeping away such common killers as heart disease and cancer. Only one doctor in 20 has a good knowledge of the growing field of "chronotherapeutics"(历史治疗术), the strategic use of time(chronos)in medicine. But according to a new American Medical Association poll, three out of four are eager to change that. "The field is exploding," says Michael Smolensky, "Doctors used to look at us like ’ What spaceship did you guys get off’ Now they’re thirsty to know more. " In medical school, most doctors learn that people with chronic conditions should take their medicine at steady rates. "It’s a terrible way to treat disease," says Dr. Richard Martin. For example, asthmatics(气喘患者)are most likely to suffer during the night. Yet most patients strive to keep a constant level of medicine in their blood day and night, whether by breathing in on an inhaler(吸入器)four times a day or taking a pill each morning and evening. In recent studies, researchers have found that a large mid-afternoon dose of a bronchodilator(支气管扩张剂)can be as safe as several small doses, and better for preventing nighttime attacks. If the night belongs to asthma, the dawn belongs to high blood pressure and heart disease. Heart attacks are twice as common at 9 a. m. as at 11 p. m. Part of the reason is that our blood pressure falls predictably at night, then peaks as we start to work for the day. "Doctors know that", says Dr. Henry Black of Chicago’s Medical Center, "but until now, we haven’t been able to do anything about it. " Most blood-pressure drugs provide 18 to 20 hours of relief. But because they’re taken in the morning, they’re least effective when most needed. "You take your pill at 7 and it’s working by 9," says Dr. William White of the University of Connecticut Health Center, "but by that time you’ve gone through the worst four hours of the day with no protection. " Bedtime dosing would prevent that lapse, but it would also push blood pressure to dangerously low levels during the night.According to the passage, how do human bodies maintain balance

A．They adjust themselves timely in line with their physical conditions.
B．People increase or lower the body temperature by sweating.
C．People’s hearts pound to compensate when the blood pressure goes up.
D．Both B and C.

单项选择题

Our bodies are wonderfully skillful at maintaining balance. When the temperature jumps, we sweat to cool down. When our blood pressure falls, our hearts pound to compensate. As it turns out, though, our natural state is not a steady one. Researchers are finding that everything from blood pressure to brain function varies rhythmically with the cycles of sun, moon and seasons. And their insights are yielding new strategies for keeping away such common killers as heart disease and cancer. Only one doctor in 20 has a good knowledge of the growing field of "chronotherapeutics"(历史治疗术), the strategic use of time(chronos)in medicine. But according to a new American Medical Association poll, three out of four are eager to change that. "The field is exploding," says Michael Smolensky, "Doctors used to look at us like ’ What spaceship did you guys get off’ Now they’re thirsty to know more. " In medical school, most doctors learn that people with chronic conditions should take their medicine at steady rates. "It’s a terrible way to treat disease," says Dr. Richard Martin. For example, asthmatics(气喘患者)are most likely to suffer during the night. Yet most patients strive to keep a constant level of medicine in their blood day and night, whether by breathing in on an inhaler(吸入器)four times a day or taking a pill each morning and evening. In recent studies, researchers have found that a large mid-afternoon dose of a bronchodilator(支气管扩张剂)can be as safe as several small doses, and better for preventing nighttime attacks. If the night belongs to asthma, the dawn belongs to high blood pressure and heart disease. Heart attacks are twice as common at 9 a. m. as at 11 p. m. Part of the reason is that our blood pressure falls predictably at night, then peaks as we start to work for the day. "Doctors know that", says Dr. Henry Black of Chicago’s Medical Center, "but until now, we haven’t been able to do anything about it. " Most blood-pressure drugs provide 18 to 20 hours of relief. But because they’re taken in the morning, they’re least effective when most needed. "You take your pill at 7 and it’s working by 9," says Dr. William White of the University of Connecticut Health Center, "but by that time you’ve gone through the worst four hours of the day with no protection. " Bedtime dosing would prevent that lapse, but it would also push blood pressure to dangerously low levels during the night.Researchers are finding that .

A．heart disease and cancer are the most common killers of human beings
B．blood pressure and brain function are decided by cycles of sun, moon and seasons
C．the functions of human bodies have much to do with nature
D．any change in human bodies goes systematically with changes in the environment

单项选择题

Our bodies are wonderfully skillful at maintaining balance. When the temperature jumps, we sweat to cool down. When our blood pressure falls, our hearts pound to compensate. As it turns out, though, our natural state is not a steady one. Researchers are finding that everything from blood pressure to brain function varies rhythmically with the cycles of sun, moon and seasons. And their insights are yielding new strategies for keeping away such common killers as heart disease and cancer. Only one doctor in 20 has a good knowledge of the growing field of "chronotherapeutics"(历史治疗术), the strategic use of time(chronos)in medicine. But according to a new American Medical Association poll, three out of four are eager to change that. "The field is exploding," says Michael Smolensky, "Doctors used to look at us like ’ What spaceship did you guys get off’ Now they’re thirsty to know more. " In medical school, most doctors learn that people with chronic conditions should take their medicine at steady rates. "It’s a terrible way to treat disease," says Dr. Richard Martin. For example, asthmatics(气喘患者)are most likely to suffer during the night. Yet most patients strive to keep a constant level of medicine in their blood day and night, whether by breathing in on an inhaler(吸入器)four times a day or taking a pill each morning and evening. In recent studies, researchers have found that a large mid-afternoon dose of a bronchodilator(支气管扩张剂)can be as safe as several small doses, and better for preventing nighttime attacks. If the night belongs to asthma, the dawn belongs to high blood pressure and heart disease. Heart attacks are twice as common at 9 a. m. as at 11 p. m. Part of the reason is that our blood pressure falls predictably at night, then peaks as we start to work for the day. "Doctors know that", says Dr. Henry Black of Chicago’s Medical Center, "but until now, we haven’t been able to do anything about it. " Most blood-pressure drugs provide 18 to 20 hours of relief. But because they’re taken in the morning, they’re least effective when most needed. "You take your pill at 7 and it’s working by 9," says Dr. William White of the University of Connecticut Health Center, "but by that time you’ve gone through the worst four hours of the day with no protection. " Bedtime dosing would prevent that lapse, but it would also push blood pressure to dangerously low levels during the night.According to the author, it is best for asthmatics to take their medicines______.

A．at steady rates
B．each morning and evening
C．when the disease occurs
D．at mid-afternoon

单项选择题

Our bodies are wonderfully skillful at maintaining balance. When the temperature jumps, we sweat to cool down. When our blood pressure falls, our hearts pound to compensate. As it turns out, though, our natural state is not a steady one. Researchers are finding that everything from blood pressure to brain function varies rhythmically with the cycles of sun, moon and seasons. And their insights are yielding new strategies for keeping away such common killers as heart disease and cancer. Only one doctor in 20 has a good knowledge of the growing field of "chronotherapeutics"(历史治疗术), the strategic use of time(chronos)in medicine. But according to a new American Medical Association poll, three out of four are eager to change that. "The field is exploding," says Michael Smolensky, "Doctors used to look at us like ’ What spaceship did you guys get off’ Now they’re thirsty to know more. " In medical school, most doctors learn that people with chronic conditions should take their medicine at steady rates. "It’s a terrible way to treat disease," says Dr. Richard Martin. For example, asthmatics(气喘患者)are most likely to suffer during the night. Yet most patients strive to keep a constant level of medicine in their blood day and night, whether by breathing in on an inhaler(吸入器)four times a day or taking a pill each morning and evening. In recent studies, researchers have found that a large mid-afternoon dose of a bronchodilator(支气管扩张剂)can be as safe as several small doses, and better for preventing nighttime attacks. If the night belongs to asthma, the dawn belongs to high blood pressure and heart disease. Heart attacks are twice as common at 9 a. m. as at 11 p. m. Part of the reason is that our blood pressure falls predictably at night, then peaks as we start to work for the day. "Doctors know that", says Dr. Henry Black of Chicago’s Medical Center, "but until now, we haven’t been able to do anything about it. " Most blood-pressure drugs provide 18 to 20 hours of relief. But because they’re taken in the morning, they’re least effective when most needed. "You take your pill at 7 and it’s working by 9," says Dr. William White of the University of Connecticut Health Center, "but by that time you’ve gone through the worst four hours of the day with no protection. " Bedtime dosing would prevent that lapse, but it would also push blood pressure to dangerously low levels during the night.Which of the following statements is NOT true

A．Doctor know more about chronotherapeutics than before.
B．Doctors in the U. S. used to be thirsty to know more about the new medical field.
C．The researchers’ insights are providing new strategies to prevent common killers.
D．The strategic use of time in medicine attracts more attention in the medical circle in the U. S.

单项选择题

Our bodies are wonderfully skillful at maintaining balance. When the temperature jumps, we sweat to cool down. When our blood pressure falls, our hearts pound to compensate. As it turns out, though, our natural state is not a steady one. Researchers are finding that everything from blood pressure to brain function varies rhythmically with the cycles of sun, moon and seasons. And their insights are yielding new strategies for keeping away such common killers as heart disease and cancer. Only one doctor in 20 has a good knowledge of the growing field of "chronotherapeutics"(历史治疗术), the strategic use of time(chronos)in medicine. But according to a new American Medical Association poll, three out of four are eager to change that. "The field is exploding," says Michael Smolensky, "Doctors used to look at us like ’ What spaceship did you guys get off’ Now they’re thirsty to know more. " In medical school, most doctors learn that people with chronic conditions should take their medicine at steady rates. "It’s a terrible way to treat disease," says Dr. Richard Martin. For example, asthmatics(气喘患者)are most likely to suffer during the night. Yet most patients strive to keep a constant level of medicine in their blood day and night, whether by breathing in on an inhaler(吸入器)four times a day or taking a pill each morning and evening. In recent studies, researchers have found that a large mid-afternoon dose of a bronchodilator(支气管扩张剂)can be as safe as several small doses, and better for preventing nighttime attacks. If the night belongs to asthma, the dawn belongs to high blood pressure and heart disease. Heart attacks are twice as common at 9 a. m. as at 11 p. m. Part of the reason is that our blood pressure falls predictably at night, then peaks as we start to work for the day. "Doctors know that", says Dr. Henry Black of Chicago’s Medical Center, "but until now, we haven’t been able to do anything about it. " Most blood-pressure drugs provide 18 to 20 hours of relief. But because they’re taken in the morning, they’re least effective when most needed. "You take your pill at 7 and it’s working by 9," says Dr. William White of the University of Connecticut Health Center, "but by that time you’ve gone through the worst four hours of the day with no protection. " Bedtime dosing would prevent that lapse, but it would also push blood pressure to dangerously low levels during the night.The suggested title for this passage might be______.

A．Medicine Is Everything
B．Treatment Is Everything
C．Timing Is Everything
D．Prevention Is Everything

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