The author includes the information ab...

The miserable fate of Enron’s employees will be a landmark in business history, one of those awful events that everyone agrees must never be allowed to happen again. This urge is understandable and noble: thousands have lost virtually all their retirement savings with the demise of Enron stock. But making sure it never happens again may not be possible, because the sudden impoverishment of those Enron workers represents something even larger than it seems. It’s the latest turn in the unwinding of one of the most audacious promise of the 20th century. The promise was assured economic security — even comfort essentially everyone in the developed world. With the explosion of wealth, that began in the 19th century it became possible to think about a possibility no one had dared to dream before. The fear at the center of daily living since caveman days — lack of food warmth, shelter — would at last lose its power to terrify. That remarkable promise became reality in many ways. Governments created welfare systems for anyone in need and separate programs for the elderly(Social Security in the U. S.). Labor unions promised not only better pay for workers but also pensions for retirees. Giant corporations came into being and offered the possibility — in some cases the promise — of lifetime employment plus guaranteed pensions. The cumulative effect was a fundamental change in how millions of people approached life itself, a reversal of attitude that most rank as one of the largest in human history. For millennia the average person’s stance toward providing for himself had been. Ultimately I’m on my own. Now it became, ultimately I’ll be taken care of... The early hints that this promise might be broken on a large scale came in the 1980s. U. S business had become uncompetitive, globally and began restructuring massively, with huge layoffs. The trend accelerated in the 1990s as the bastions of corporate welfare faced reality. IBM ended its no-layoff policy. AT&T fired thousands, many of whom found such a thing simply incomprehensible, and a few of whom killed themselves. The other supposed guarantors of our economic security were also in decline. Labor -union membership and power fell to their lowest levels in decades. President Clinton signed a historic bill scaling back welfare. Americans realized that Social Security won’t provide social security for any of us. A less visible but equally significant trend a affected pensions. To make costs easier to control, companies moved away from defined benefit pension plans, which obligate them to pay out specified amounts years in the future, to define contribution plans, which specify only how much goes into the play today. The most common type of defined-contribution plan is the 401(k). The significance of the 401(k)is that it puts most of the responsibility for a person’s economic fate back on the employee. Within limits the employee must decide how much goes into the plan each year and how it gets invested-the two factors that will determine how much it’s worth when the employee retires. Which brings us back to Eaton Those billions of dollars in vaporized retirement savings went in employees’ 401(k)accounts. That is, the employees chose how much money to put into those accounts arid then chose bow to invest it. Enron matched a certain proportion of each employee’s 401(k)contribution with company stock, so everyone was going to end up with some Eaton ha his or her portfolio, but that could be regarded as a freebie, since nothing compels a company to match employee contributions at all. At least two special features complicate the Eaton case. First, same shareholders charge top management with illegally covering up the company’s problems, prompting investors to hang on when they should have sold. Second, Enron’s 401(k)accounts were lacked while the company changed plan administrators in October, when the stock was failing, so employees could not have closed their accounts if they wanted to. But by far the largest cause of this human tragedy is that thousands of employees were heavily overweighed in Eaton stock. Many had placed 100% of their 401(k)assets in the stock rather than in the 18 other investment options they were offered. Of course that wasn’t prudent, but it’s what some of them did. The Enron employees’ retirement disaster is part of the larger trend away from guaranteed economic security. That’s why preventing such a thing from ever happening again may be impossible. The huge attitudinal shift to I’ll-be-taken-care-of took at least a generation. The shift back may take just as long. It won’t be complete until a new generation of employees see assured economic comfort as a 20th-century quirk, and understand not just intellectually but in their bones that, like most people in most times and places, they’re on their own.According to the passage, the combined efforts by governments, layout unions and big corporations to guarantee economic comfort have led to a significant change in______.

A．people’s outlook on life
B．people’s social values
C．people’s living standard
D．people’s life styles

The miserable fate of Enron’s employees will be a landmark in business history, one of those awful events that everyone agrees must never be allowed to happen again. This urge is understandable and noble: thousands have lost virtually all their retirement savings with the demise of Enron stock. But making sure it never happens again may not be possible, because the sudden impoverishment of those Enron workers represents something even larger than it seems. It’s the latest turn in the unwinding of one of the most audacious promise of the 20th century. The promise was assured economic security — even comfort essentially everyone in the developed world. With the explosion of wealth, that began in the 19th century it became possible to think about a possibility no one had dared to dream before. The fear at the center of daily living since caveman days — lack of food warmth, shelter — would at last lose its power to terrify. That remarkable promise became reality in many ways. Governments created welfare systems for anyone in need and separate programs for the elderly(Social Security in the U. S.). Labor unions promised not only better pay for workers but also pensions for retirees. Giant corporations came into being and offered the possibility — in some cases the promise — of lifetime employment plus guaranteed pensions. The cumulative effect was a fundamental change in how millions of people approached life itself, a reversal of attitude that most rank as one of the largest in human history. For millennia the average person’s stance toward providing for himself had been. Ultimately I’m on my own. Now it became, ultimately I’ll be taken care of... The early hints that this promise might be broken on a large scale came in the 1980s. U. S business had become uncompetitive, globally and began restructuring massively, with huge layoffs. The trend accelerated in the 1990s as the bastions of corporate welfare faced reality. IBM ended its no-layoff policy. AT&T fired thousands, many of whom found such a thing simply incomprehensible, and a few of whom killed themselves. The other supposed guarantors of our economic security were also in decline. Labor -union membership and power fell to their lowest levels in decades. President Clinton signed a historic bill scaling back welfare. Americans realized that Social Security won’t provide social security for any of us. A less visible but equally significant trend a affected pensions. To make costs easier to control, companies moved away from defined benefit pension plans, which obligate them to pay out specified amounts years in the future, to define contribution plans, which specify only how much goes into the play today. The most common type of defined-contribution plan is the 401(k). The significance of the 401(k)is that it puts most of the responsibility for a person’s economic fate back on the employee. Within limits the employee must decide how much goes into the plan each year and how it gets invested-the two factors that will determine how much it’s worth when the employee retires. Which brings us back to Eaton Those billions of dollars in vaporized retirement savings went in employees’ 401(k)accounts. That is, the employees chose how much money to put into those accounts arid then chose bow to invest it. Enron matched a certain proportion of each employee’s 401(k)contribution with company stock, so everyone was going to end up with some Eaton ha his or her portfolio, but that could be regarded as a freebie, since nothing compels a company to match employee contributions at all. At least two special features complicate the Eaton case. First, same shareholders charge top management with illegally covering up the company’s problems, prompting investors to hang on when they should have sold. Second, Enron’s 401(k)accounts were lacked while the company changed plan administrators in October, when the stock was failing, so employees could not have closed their accounts if they wanted to. But by far the largest cause of this human tragedy is that thousands of employees were heavily overweighed in Eaton stock. Many had placed 100% of their 401(k)assets in the stock rather than in the 18 other investment options they were offered. Of course that wasn’t prudent, but it’s what some of them did. The Enron employees’ retirement disaster is part of the larger trend away from guaranteed economic security. That’s why preventing such a thing from ever happening again may be impossible. The huge attitudinal shift to I’ll-be-taken-care-of took at least a generation. The shift back may take just as long. It won’t be complete until a new generation of employees see assured economic comfort as a 20th-century quirk, and understand not just intellectually but in their bones that, like most people in most times and places, they’re on their own.Changes in pension schemes were also part of______.

A．the corporate lay-offs
B．the warning power of labors unions
C．the economic restructuring
D．The government cuts in welfare spending

单项选择题

The miserable fate of Enron’s employees will be a landmark in business history, one of those awful events that everyone agrees must never be allowed to happen again. This urge is understandable and noble: thousands have lost virtually all their retirement savings with the demise of Enron stock. But making sure it never happens again may not be possible, because the sudden impoverishment of those Enron workers represents something even larger than it seems. It’s the latest turn in the unwinding of one of the most audacious promise of the 20th century. The promise was assured economic security — even comfort essentially everyone in the developed world. With the explosion of wealth, that began in the 19th century it became possible to think about a possibility no one had dared to dream before. The fear at the center of daily living since caveman days — lack of food warmth, shelter — would at last lose its power to terrify. That remarkable promise became reality in many ways. Governments created welfare systems for anyone in need and separate programs for the elderly(Social Security in the U. S.). Labor unions promised not only better pay for workers but also pensions for retirees. Giant corporations came into being and offered the possibility — in some cases the promise — of lifetime employment plus guaranteed pensions. The cumulative effect was a fundamental change in how millions of people approached life itself, a reversal of attitude that most rank as one of the largest in human history. For millennia the average person’s stance toward providing for himself had been. Ultimately I’m on my own. Now it became, ultimately I’ll be taken care of... The early hints that this promise might be broken on a large scale came in the 1980s. U. S business had become uncompetitive, globally and began restructuring massively, with huge layoffs. The trend accelerated in the 1990s as the bastions of corporate welfare faced reality. IBM ended its no-layoff policy. AT&T fired thousands, many of whom found such a thing simply incomprehensible, and a few of whom killed themselves. The other supposed guarantors of our economic security were also in decline. Labor -union membership and power fell to their lowest levels in decades. President Clinton signed a historic bill scaling back welfare. Americans realized that Social Security won’t provide social security for any of us. A less visible but equally significant trend a affected pensions. To make costs easier to control, companies moved away from defined benefit pension plans, which obligate them to pay out specified amounts years in the future, to define contribution plans, which specify only how much goes into the play today. The most common type of defined-contribution plan is the 401(k). The significance of the 401(k)is that it puts most of the responsibility for a person’s economic fate back on the employee. Within limits the employee must decide how much goes into the plan each year and how it gets invested-the two factors that will determine how much it’s worth when the employee retires. Which brings us back to Eaton Those billions of dollars in vaporized retirement savings went in employees’ 401(k)accounts. That is, the employees chose how much money to put into those accounts arid then chose bow to invest it. Enron matched a certain proportion of each employee’s 401(k)contribution with company stock, so everyone was going to end up with some Eaton ha his or her portfolio, but that could be regarded as a freebie, since nothing compels a company to match employee contributions at all. At least two special features complicate the Eaton case. First, same shareholders charge top management with illegally covering up the company’s problems, prompting investors to hang on when they should have sold. Second, Enron’s 401(k)accounts were lacked while the company changed plan administrators in October, when the stock was failing, so employees could not have closed their accounts if they wanted to. But by far the largest cause of this human tragedy is that thousands of employees were heavily overweighed in Eaton stock. Many had placed 100% of their 401(k)assets in the stock rather than in the 18 other investment options they were offered. Of course that wasn’t prudent, but it’s what some of them did. The Enron employees’ retirement disaster is part of the larger trend away from guaranteed economic security. That’s why preventing such a thing from ever happening again may be impossible. The huge attitudinal shift to I’ll-be-taken-care-of took at least a generation. The shift back may take just as long. It won’t be complete until a new generation of employees see assured economic comfort as a 20th-century quirk, and understand not just intellectually but in their bones that, like most people in most times and places, they’re on their own.Thousands of employees chose Eaton as their sole investment option mainly because______.

A．the 401(k)made them responsible for their own future
B．Enron offered company stock to their investment
C．their employers intended to cut back on pension spending
D．Enron’s offer was similar to a defmed-benefit plan

单项选择题

The miserable fate of Enron’s employees will be a landmark in business history, one of those awful events that everyone agrees must never be allowed to happen again. This urge is understandable and noble: thousands have lost virtually all their retirement savings with the demise of Enron stock. But making sure it never happens again may not be possible, because the sudden impoverishment of those Enron workers represents something even larger than it seems. It’s the latest turn in the unwinding of one of the most audacious promise of the 20th century. The promise was assured economic security — even comfort essentially everyone in the developed world. With the explosion of wealth, that began in the 19th century it became possible to think about a possibility no one had dared to dream before. The fear at the center of daily living since caveman days — lack of food warmth, shelter — would at last lose its power to terrify. That remarkable promise became reality in many ways. Governments created welfare systems for anyone in need and separate programs for the elderly(Social Security in the U. S.). Labor unions promised not only better pay for workers but also pensions for retirees. Giant corporations came into being and offered the possibility — in some cases the promise — of lifetime employment plus guaranteed pensions. The cumulative effect was a fundamental change in how millions of people approached life itself, a reversal of attitude that most rank as one of the largest in human history. For millennia the average person’s stance toward providing for himself had been. Ultimately I’m on my own. Now it became, ultimately I’ll be taken care of... The early hints that this promise might be broken on a large scale came in the 1980s. U. S business had become uncompetitive, globally and began restructuring massively, with huge layoffs. The trend accelerated in the 1990s as the bastions of corporate welfare faced reality. IBM ended its no-layoff policy. AT&T fired thousands, many of whom found such a thing simply incomprehensible, and a few of whom killed themselves. The other supposed guarantors of our economic security were also in decline. Labor -union membership and power fell to their lowest levels in decades. President Clinton signed a historic bill scaling back welfare. Americans realized that Social Security won’t provide social security for any of us. A less visible but equally significant trend a affected pensions. To make costs easier to control, companies moved away from defined benefit pension plans, which obligate them to pay out specified amounts years in the future, to define contribution plans, which specify only how much goes into the play today. The most common type of defined-contribution plan is the 401(k). The significance of the 401(k)is that it puts most of the responsibility for a person’s economic fate back on the employee. Within limits the employee must decide how much goes into the plan each year and how it gets invested-the two factors that will determine how much it’s worth when the employee retires. Which brings us back to Eaton Those billions of dollars in vaporized retirement savings went in employees’ 401(k)accounts. That is, the employees chose how much money to put into those accounts arid then chose bow to invest it. Enron matched a certain proportion of each employee’s 401(k)contribution with company stock, so everyone was going to end up with some Eaton ha his or her portfolio, but that could be regarded as a freebie, since nothing compels a company to match employee contributions at all. At least two special features complicate the Eaton case. First, same shareholders charge top management with illegally covering up the company’s problems, prompting investors to hang on when they should have sold. Second, Enron’s 401(k)accounts were lacked while the company changed plan administrators in October, when the stock was failing, so employees could not have closed their accounts if they wanted to. But by far the largest cause of this human tragedy is that thousands of employees were heavily overweighed in Eaton stock. Many had placed 100% of their 401(k)assets in the stock rather than in the 18 other investment options they were offered. Of course that wasn’t prudent, but it’s what some of them did. The Enron employees’ retirement disaster is part of the larger trend away from guaranteed economic security. That’s why preventing such a thing from ever happening again may be impossible. The huge attitudinal shift to I’ll-be-taken-care-of took at least a generation. The shift back may take just as long. It won’t be complete until a new generation of employees see assured economic comfort as a 20th-century quirk, and understand not just intellectually but in their bones that, like most people in most times and places, they’re on their own.Which is NOT seen as a lesson drawn from the Eaton disaster

A．401(k)assets should be placed in more than one investment option.
B．Such events could happen again as it is ns not easy to change people’s mind.
C．Employees have to take up responsibilities for themselves.
D．Economic security won’t be taken for granted by future young workers.

单项选择题

Statins are a class of drugs that work to decrease the level of cholesterol in the blood. They are able to perform this function by effectively blocking the cholesterol -producing enzyme in the liver. In recent years, statins have increased in utility and popularity. Although a certain amount of cholesterol is imperative for the human body to function, an elevated level can cause a precarious situation in the body. Cholesterol affixes itself to arteries, lining them and inhibiting blood flow. Since less blood can travel through those encumbered arteries, the blood flow to the heart is adversely affected. Scientists have found that the walls of arteries in the body can become inflamed from this plaque buildup. In many instances, the end result of this decreased blood supply and inflammation is a heart attack — sometimes a fatal one. In other, cases the blood supply to the brain is compromised by file plaque, often causing a stroke. Decreased blood flow to the legs can cause leg palms or cramps. In short, arterial plaque buildup is never a healthy situation. Statins diminish the amount of cholesterol generated by the b body. Although the drugs are not always able to reduce the amount of plaque that may already be clogging arteries, they can slow the production of new plaque. The drugs are also able to stabilize the plaques that are already present and make them less likely to cause problems in the body. Lowered cholesterol does not guarantee that a heart attack won’t occur, but statin use will lower the risk for most patients. Not everyone who has a heart attack has high cholesterol levels, but most do have plaque formations on their arteries. It should be noted that the plaque is not always formed by high levels of cholesterol in the blood. Statins are generally prescribed by doctors for people with elevated cholesterol levels. As the mean weight of the American population has risen, so has the number of individuals with high cholesterol. Millions of men and women in this country are prescribed statins in an effort to decrease the amount of cholesterol in their blood. Remarkably, these effects eau be seen in as little as two weeks after beginning a statin regime.Which of the following is suggested about the American population

A．Their life expectancy has decreased in the past few decades.
B．There are a record number of heart disease deaths in the United States.
C．Their diet may be affecting their cholesterol levels.
D．They want an easy fix for a difficult problem.

单项选择题

The miserable fate of Enron’s employees will be a landmark in business history, one of those awful events that everyone agrees must never be allowed to happen again. This urge is understandable and noble: thousands have lost virtually all their retirement savings with the demise of Enron stock. But making sure it never happens again may not be possible, because the sudden impoverishment of those Enron workers represents something even larger than it seems. It’s the latest turn in the unwinding of one of the most audacious promise of the 20th century. The promise was assured economic security — even comfort essentially everyone in the developed world. With the explosion of wealth, that began in the 19th century it became possible to think about a possibility no one had dared to dream before. The fear at the center of daily living since caveman days — lack of food warmth, shelter — would at last lose its power to terrify. That remarkable promise became reality in many ways. Governments created welfare systems for anyone in need and separate programs for the elderly(Social Security in the U. S.). Labor unions promised not only better pay for workers but also pensions for retirees. Giant corporations came into being and offered the possibility — in some cases the promise — of lifetime employment plus guaranteed pensions. The cumulative effect was a fundamental change in how millions of people approached life itself, a reversal of attitude that most rank as one of the largest in human history. For millennia the average person’s stance toward providing for himself had been. Ultimately I’m on my own. Now it became, ultimately I’ll be taken care of... The early hints that this promise might be broken on a large scale came in the 1980s. U. S business had become uncompetitive, globally and began restructuring massively, with huge layoffs. The trend accelerated in the 1990s as the bastions of corporate welfare faced reality. IBM ended its no-layoff policy. AT&T fired thousands, many of whom found such a thing simply incomprehensible, and a few of whom killed themselves. The other supposed guarantors of our economic security were also in decline. Labor -union membership and power fell to their lowest levels in decades. President Clinton signed a historic bill scaling back welfare. Americans realized that Social Security won’t provide social security for any of us. A less visible but equally significant trend a affected pensions. To make costs easier to control, companies moved away from defined benefit pension plans, which obligate them to pay out specified amounts years in the future, to define contribution plans, which specify only how much goes into the play today. The most common type of defined-contribution plan is the 401(k). The significance of the 401(k)is that it puts most of the responsibility for a person’s economic fate back on the employee. Within limits the employee must decide how much goes into the plan each year and how it gets invested-the two factors that will determine how much it’s worth when the employee retires. Which brings us back to Eaton Those billions of dollars in vaporized retirement savings went in employees’ 401(k)accounts. That is, the employees chose how much money to put into those accounts arid then chose bow to invest it. Enron matched a certain proportion of each employee’s 401(k)contribution with company stock, so everyone was going to end up with some Eaton ha his or her portfolio, but that could be regarded as a freebie, since nothing compels a company to match employee contributions at all. At least two special features complicate the Eaton case. First, same shareholders charge top management with illegally covering up the company’s problems, prompting investors to hang on when they should have sold. Second, Enron’s 401(k)accounts were lacked while the company changed plan administrators in October, when the stock was failing, so employees could not have closed their accounts if they wanted to. But by far the largest cause of this human tragedy is that thousands of employees were heavily overweighed in Eaton stock. Many had placed 100% of their 401(k)assets in the stock rather than in the 18 other investment options they were offered. Of course that wasn’t prudent, but it’s what some of them did. The Enron employees’ retirement disaster is part of the larger trend away from guaranteed economic security. That’s why preventing such a thing from ever happening again may be impossible. The huge attitudinal shift to I’ll-be-taken-care-of took at least a generation. The shift back may take just as long. It won’t be complete until a new generation of employees see assured economic comfort as a 20th-century quirk, and understand not just intellectually but in their bones that, like most people in most times and places, they’re on their own.Why does the author say at the beginning "The miserable fate of Enron’s employees will be a landmark in business history..."

A．Because the company has gone bankrupt.
B．Because it signifies a turning point in economic security.
C．Because many Enron workers lost their retirement savings.
D．Because such events would never happen again.

单项选择题

Statins are a class of drugs that work to decrease the level of cholesterol in the blood. They are able to perform this function by effectively blocking the cholesterol -producing enzyme in the liver. In recent years, statins have increased in utility and popularity. Although a certain amount of cholesterol is imperative for the human body to function, an elevated level can cause a precarious situation in the body. Cholesterol affixes itself to arteries, lining them and inhibiting blood flow. Since less blood can travel through those encumbered arteries, the blood flow to the heart is adversely affected. Scientists have found that the walls of arteries in the body can become inflamed from this plaque buildup. In many instances, the end result of this decreased blood supply and inflammation is a heart attack — sometimes a fatal one. In other, cases the blood supply to the brain is compromised by file plaque, often causing a stroke. Decreased blood flow to the legs can cause leg palms or cramps. In short, arterial plaque buildup is never a healthy situation. Statins diminish the amount of cholesterol generated by the b body. Although the drugs are not always able to reduce the amount of plaque that may already be clogging arteries, they can slow the production of new plaque. The drugs are also able to stabilize the plaques that are already present and make them less likely to cause problems in the body. Lowered cholesterol does not guarantee that a heart attack won’t occur, but statin use will lower the risk for most patients. Not everyone who has a heart attack has high cholesterol levels, but most do have plaque formations on their arteries. It should be noted that the plaque is not always formed by high levels of cholesterol in the blood. Statins are generally prescribed by doctors for people with elevated cholesterol levels. As the mean weight of the American population has risen, so has the number of individuals with high cholesterol. Millions of men and women in this country are prescribed statins in an effort to decrease the amount of cholesterol in their blood. Remarkably, these effects eau be seen in as little as two weeks after beginning a statin regime.The author concedes that statins’ job is primarily to______.

A．attack the cholesterol in the human body
B．eliminate the possibility of a heart attack
C．increase the amount of blood flowing to the heart
D．slow the production of cholesterol in the body

单项选择题

Several hundred million years ago, plants similar to modern ferns covered vast stretches of the land. Some were as large as trees, with giant fronds bunched at the top of trunks as straight as pillars. Others were the size of bushes and formed thickets of me undergrowth. Still others lived in the shade of giant club mosses and horsetails along the edges of swampy lagoons where giant amphibians swam. A great number of these plants were true ferns, reproducing themselves without fruits or seeds. Others had only the appearance of ferns. Their leaves had organs of sexual reproduction and produced seeds. Although their "flowers" did not have corollas these false ferns(today completely extinct)ushered in the era of flowering plants. Traces of these floras of the earliest times have been preserved in the form of fossils. Such traces are most commonly found in shale and sandstone rocks wedged between coal beds. Today only tropical forests bear living proof of tile ancient greatness of ferns. The species that grow there are no longer those of the Carboniferous period, but their variety and vast numbers, and the great size of some, remind us of the time when ferns ruled the plant kingdom.Which of the following is NOT mentioned as a characteristic of the plants described in the passage

A．They once spread over large areas of land.
B．They varied greatly in size.
C．They coexisted with amphibians, mosses, and horsetails.
D．They clung to tree trunks and bushes for support.

单项选择题

Statins are a class of drugs that work to decrease the level of cholesterol in the blood. They are able to perform this function by effectively blocking the cholesterol -producing enzyme in the liver. In recent years, statins have increased in utility and popularity. Although a certain amount of cholesterol is imperative for the human body to function, an elevated level can cause a precarious situation in the body. Cholesterol affixes itself to arteries, lining them and inhibiting blood flow. Since less blood can travel through those encumbered arteries, the blood flow to the heart is adversely affected. Scientists have found that the walls of arteries in the body can become inflamed from this plaque buildup. In many instances, the end result of this decreased blood supply and inflammation is a heart attack — sometimes a fatal one. In other, cases the blood supply to the brain is compromised by file plaque, often causing a stroke. Decreased blood flow to the legs can cause leg palms or cramps. In short, arterial plaque buildup is never a healthy situation. Statins diminish the amount of cholesterol generated by the b body. Although the drugs are not always able to reduce the amount of plaque that may already be clogging arteries, they can slow the production of new plaque. The drugs are also able to stabilize the plaques that are already present and make them less likely to cause problems in the body. Lowered cholesterol does not guarantee that a heart attack won’t occur, but statin use will lower the risk for most patients. Not everyone who has a heart attack has high cholesterol levels, but most do have plaque formations on their arteries. It should be noted that the plaque is not always formed by high levels of cholesterol in the blood. Statins are generally prescribed by doctors for people with elevated cholesterol levels. As the mean weight of the American population has risen, so has the number of individuals with high cholesterol. Millions of men and women in this country are prescribed statins in an effort to decrease the amount of cholesterol in their blood. Remarkably, these effects eau be seen in as little as two weeks after beginning a statin regime.The author organizes the passage by______.

A．enumerating reasons why statins are useful drugs
B．debating the importance of statins
C．criticizing the American public’s diet and health
D．outlining ways to reduce cholesterol in the blood

单项选择题

Chlorine is a mainstay in most swimming pools in the United States, and is used to eradicate bacteria. A bacteria-free pool will usually ensure that swimmers won’t contract a serious illness if they spend time in, and possibly ingest, the water. When chlorine is added to pool water, a chemical reaction occurs whereby the chlorine breaks down into a legion of chemicals that combine to kill bacteria that may be in water. These chemicals, specifically hypochlorous acid and hypochlorite ion, eliminate bacteria by annihilating and then oxidizing the abhorrent cells. When this chemical reaction occurs, the baeteria are rendered essentially harmless. This chemical reaction doesn’t occur immediately — individual components within chlorine take varying amounts of time to interact with the bacteria, creating an almost time-release-type of kill in the pool water. Chlorine must be regularly replenished. As they react, the hypochlorous acid and hypochlorite ion combine to create a particular acceptable pH level in the pool water. A pH is a measure of the alkalinity and acidity present; a pH value of 7 represents a neutral value, and 7. 4 is the pH value of the human tear. The pH ratio must be regularly monitored to ensure a consistent optimum ram — one usually kept within the spectrum of 7 to 8 as measured by a reliable pH measuring kit. As the chemicals in chlorine complete their reactions, they break down and are no longer effective in keeping the pool water neutralized. Additional chlorine must be added to water at specific times. Outdoor pools that are in direct sunlight need to have water added more often because the chemical reaction time for chlorine is increased and its effectiveness is reduced in these conditions. Since the hypochlorite ion is an especially potent chemical capable of fading fabrics and paint, most people are meticulous about rinsing chlorine from potentially affected areas. Although chlorine is inexpensive and widely available, some people find the bleach smell to be repugnant and the distinct aroma present at many swimming pools to be overwhelming. These people may not be able to enjoy aquatic pursuits in those pools that employ chlorine as a cleansing agent. Other people may find that inhaling chlorine at the high levels present around some pools may be difficult to tolerate. Still others may experience skin irritation after swimming in a pool containing chlorine. Although there are other chemicals and compounds available to clean swimming pools, they may be prohibitively expensive or incapable of killing all types of bacteria present in the water.According to the passage, a stable pH value in pool water is dependent upon which of the following

A．Monitoring and adding chlorine when warranted.
B．Ensuring that there is only a minimum amount of bacteria in the water.
C．Paying close attention to the reactions of chemicals in the pool water.
D．Ensuring that water is protected from direct sunlight.

单项选择题

Several hundred million years ago, plants similar to modern ferns covered vast stretches of the land. Some were as large as trees, with giant fronds bunched at the top of trunks as straight as pillars. Others were the size of bushes and formed thickets of me undergrowth. Still others lived in the shade of giant club mosses and horsetails along the edges of swampy lagoons where giant amphibians swam. A great number of these plants were true ferns, reproducing themselves without fruits or seeds. Others had only the appearance of ferns. Their leaves had organs of sexual reproduction and produced seeds. Although their "flowers" did not have corollas these false ferns(today completely extinct)ushered in the era of flowering plants. Traces of these floras of the earliest times have been preserved in the form of fossils. Such traces are most commonly found in shale and sandstone rocks wedged between coal beds. Today only tropical forests bear living proof of tile ancient greatness of ferns. The species that grow there are no longer those of the Carboniferous period, but their variety and vast numbers, and the great size of some, remind us of the time when ferns ruled the plant kingdom.What does the passage mainly discuss

A．Plant reproduction.
B．An ancient form of plant life.
C．How to locate fossils.
D．Tropical plant life.

单项选择题

Statins are a class of drugs that work to decrease the level of cholesterol in the blood. They are able to perform this function by effectively blocking the cholesterol -producing enzyme in the liver. In recent years, statins have increased in utility and popularity. Although a certain amount of cholesterol is imperative for the human body to function, an elevated level can cause a precarious situation in the body. Cholesterol affixes itself to arteries, lining them and inhibiting blood flow. Since less blood can travel through those encumbered arteries, the blood flow to the heart is adversely affected. Scientists have found that the walls of arteries in the body can become inflamed from this plaque buildup. In many instances, the end result of this decreased blood supply and inflammation is a heart attack — sometimes a fatal one. In other, cases the blood supply to the brain is compromised by file plaque, often causing a stroke. Decreased blood flow to the legs can cause leg palms or cramps. In short, arterial plaque buildup is never a healthy situation. Statins diminish the amount of cholesterol generated by the b body. Although the drugs are not always able to reduce the amount of plaque that may already be clogging arteries, they can slow the production of new plaque. The drugs are also able to stabilize the plaques that are already present and make them less likely to cause problems in the body. Lowered cholesterol does not guarantee that a heart attack won’t occur, but statin use will lower the risk for most patients. Not everyone who has a heart attack has high cholesterol levels, but most do have plaque formations on their arteries. It should be noted that the plaque is not always formed by high levels of cholesterol in the blood. Statins are generally prescribed by doctors for people with elevated cholesterol levels. As the mean weight of the American population has risen, so has the number of individuals with high cholesterol. Millions of men and women in this country are prescribed statins in an effort to decrease the amount of cholesterol in their blood. Remarkably, these effects eau be seen in as little as two weeks after beginning a statin regime.The author’s main point is that______.

A．statins can diminish the amount of cholesterol in the blood
B．heart attacks are not the only danger of high cholesterol
C．most people have plaque buildup in their arteries
D．statins are not able to decrease the amount of plaque lining the arteries

单项选择题

Chlorine is a mainstay in most swimming pools in the United States, and is used to eradicate bacteria. A bacteria-free pool will usually ensure that swimmers won’t contract a serious illness if they spend time in, and possibly ingest, the water. When chlorine is added to pool water, a chemical reaction occurs whereby the chlorine breaks down into a legion of chemicals that combine to kill bacteria that may be in water. These chemicals, specifically hypochlorous acid and hypochlorite ion, eliminate bacteria by annihilating and then oxidizing the abhorrent cells. When this chemical reaction occurs, the baeteria are rendered essentially harmless. This chemical reaction doesn’t occur immediately — individual components within chlorine take varying amounts of time to interact with the bacteria, creating an almost time-release-type of kill in the pool water. Chlorine must be regularly replenished. As they react, the hypochlorous acid and hypochlorite ion combine to create a particular acceptable pH level in the pool water. A pH is a measure of the alkalinity and acidity present; a pH value of 7 represents a neutral value, and 7. 4 is the pH value of the human tear. The pH ratio must be regularly monitored to ensure a consistent optimum ram — one usually kept within the spectrum of 7 to 8 as measured by a reliable pH measuring kit. As the chemicals in chlorine complete their reactions, they break down and are no longer effective in keeping the pool water neutralized. Additional chlorine must be added to water at specific times. Outdoor pools that are in direct sunlight need to have water added more often because the chemical reaction time for chlorine is increased and its effectiveness is reduced in these conditions. Since the hypochlorite ion is an especially potent chemical capable of fading fabrics and paint, most people are meticulous about rinsing chlorine from potentially affected areas. Although chlorine is inexpensive and widely available, some people find the bleach smell to be repugnant and the distinct aroma present at many swimming pools to be overwhelming. These people may not be able to enjoy aquatic pursuits in those pools that employ chlorine as a cleansing agent. Other people may find that inhaling chlorine at the high levels present around some pools may be difficult to tolerate. Still others may experience skin irritation after swimming in a pool containing chlorine. Although there are other chemicals and compounds available to clean swimming pools, they may be prohibitively expensive or incapable of killing all types of bacteria present in the water.The author’s primary purpose is to______.

A．offer an unbiased opinion of chlorine’s efficacy
B．provide an argument for using chlorine
C．discuss the chemical reaction taking place within a pool
D．show how chlorine can keep pool water safe

单项选择题

Chlorine is a mainstay in most swimming pools in the United States, and is used to eradicate bacteria. A bacteria-free pool will usually ensure that swimmers won’t contract a serious illness if they spend time in, and possibly ingest, the water. When chlorine is added to pool water, a chemical reaction occurs whereby the chlorine breaks down into a legion of chemicals that combine to kill bacteria that may be in water. These chemicals, specifically hypochlorous acid and hypochlorite ion, eliminate bacteria by annihilating and then oxidizing the abhorrent cells. When this chemical reaction occurs, the baeteria are rendered essentially harmless. This chemical reaction doesn’t occur immediately — individual components within chlorine take varying amounts of time to interact with the bacteria, creating an almost time-release-type of kill in the pool water. Chlorine must be regularly replenished. As they react, the hypochlorous acid and hypochlorite ion combine to create a particular acceptable pH level in the pool water. A pH is a measure of the alkalinity and acidity present; a pH value of 7 represents a neutral value, and 7. 4 is the pH value of the human tear. The pH ratio must be regularly monitored to ensure a consistent optimum ram — one usually kept within the spectrum of 7 to 8 as measured by a reliable pH measuring kit. As the chemicals in chlorine complete their reactions, they break down and are no longer effective in keeping the pool water neutralized. Additional chlorine must be added to water at specific times. Outdoor pools that are in direct sunlight need to have water added more often because the chemical reaction time for chlorine is increased and its effectiveness is reduced in these conditions. Since the hypochlorite ion is an especially potent chemical capable of fading fabrics and paint, most people are meticulous about rinsing chlorine from potentially affected areas. Although chlorine is inexpensive and widely available, some people find the bleach smell to be repugnant and the distinct aroma present at many swimming pools to be overwhelming. These people may not be able to enjoy aquatic pursuits in those pools that employ chlorine as a cleansing agent. Other people may find that inhaling chlorine at the high levels present around some pools may be difficult to tolerate. Still others may experience skin irritation after swimming in a pool containing chlorine. Although there are other chemicals and compounds available to clean swimming pools, they may be prohibitively expensive or incapable of killing all types of bacteria present in the water.Based on the passage, which statement is probably NOT true of chlorine

A．It can be harmful if swallowed.
B．Occasional high levels in pool water arc probably not harmful.
C．It can kill most common types of pool water bacteria.
D．A pool’s size will dictate the amount needed.

单项选择题

Chlorine is a mainstay in most swimming pools in the United States, and is used to eradicate bacteria. A bacteria-free pool will usually ensure that swimmers won’t contract a serious illness if they spend time in, and possibly ingest, the water. When chlorine is added to pool water, a chemical reaction occurs whereby the chlorine breaks down into a legion of chemicals that combine to kill bacteria that may be in water. These chemicals, specifically hypochlorous acid and hypochlorite ion, eliminate bacteria by annihilating and then oxidizing the abhorrent cells. When this chemical reaction occurs, the baeteria are rendered essentially harmless. This chemical reaction doesn’t occur immediately — individual components within chlorine take varying amounts of time to interact with the bacteria, creating an almost time-release-type of kill in the pool water. Chlorine must be regularly replenished. As they react, the hypochlorous acid and hypochlorite ion combine to create a particular acceptable pH level in the pool water. A pH is a measure of the alkalinity and acidity present; a pH value of 7 represents a neutral value, and 7. 4 is the pH value of the human tear. The pH ratio must be regularly monitored to ensure a consistent optimum ram — one usually kept within the spectrum of 7 to 8 as measured by a reliable pH measuring kit. As the chemicals in chlorine complete their reactions, they break down and are no longer effective in keeping the pool water neutralized. Additional chlorine must be added to water at specific times. Outdoor pools that are in direct sunlight need to have water added more often because the chemical reaction time for chlorine is increased and its effectiveness is reduced in these conditions. Since the hypochlorite ion is an especially potent chemical capable of fading fabrics and paint, most people are meticulous about rinsing chlorine from potentially affected areas. Although chlorine is inexpensive and widely available, some people find the bleach smell to be repugnant and the distinct aroma present at many swimming pools to be overwhelming. These people may not be able to enjoy aquatic pursuits in those pools that employ chlorine as a cleansing agent. Other people may find that inhaling chlorine at the high levels present around some pools may be difficult to tolerate. Still others may experience skin irritation after swimming in a pool containing chlorine. Although there are other chemicals and compounds available to clean swimming pools, they may be prohibitively expensive or incapable of killing all types of bacteria present in the water.The author includes the information about the pH of human tears mainly to______.

A．give the reader a base of reference
B．personalize the passage to enhance interest
C．provide a visual image for the reader
D．answer the reader’s anticipated question

单项选择题

Chlorine is a mainstay in most swimming pools in the United States, and is used to eradicate bacteria. A bacteria-free pool will usually ensure that swimmers won’t contract a serious illness if they spend time in, and possibly ingest, the water. When chlorine is added to pool water, a chemical reaction occurs whereby the chlorine breaks down into a legion of chemicals that combine to kill bacteria that may be in water. These chemicals, specifically hypochlorous acid and hypochlorite ion, eliminate bacteria by annihilating and then oxidizing the abhorrent cells. When this chemical reaction occurs, the baeteria are rendered essentially harmless. This chemical reaction doesn’t occur immediately — individual components within chlorine take varying amounts of time to interact with the bacteria, creating an almost time-release-type of kill in the pool water. Chlorine must be regularly replenished. As they react, the hypochlorous acid and hypochlorite ion combine to create a particular acceptable pH level in the pool water. A pH is a measure of the alkalinity and acidity present; a pH value of 7 represents a neutral value, and 7. 4 is the pH value of the human tear. The pH ratio must be regularly monitored to ensure a consistent optimum ram — one usually kept within the spectrum of 7 to 8 as measured by a reliable pH measuring kit. As the chemicals in chlorine complete their reactions, they break down and are no longer effective in keeping the pool water neutralized. Additional chlorine must be added to water at specific times. Outdoor pools that are in direct sunlight need to have water added more often because the chemical reaction time for chlorine is increased and its effectiveness is reduced in these conditions. Since the hypochlorite ion is an especially potent chemical capable of fading fabrics and paint, most people are meticulous about rinsing chlorine from potentially affected areas. Although chlorine is inexpensive and widely available, some people find the bleach smell to be repugnant and the distinct aroma present at many swimming pools to be overwhelming. These people may not be able to enjoy aquatic pursuits in those pools that employ chlorine as a cleansing agent. Other people may find that inhaling chlorine at the high levels present around some pools may be difficult to tolerate. Still others may experience skin irritation after swimming in a pool containing chlorine. Although there are other chemicals and compounds available to clean swimming pools, they may be prohibitively expensive or incapable of killing all types of bacteria present in the water.All of the following statements are true about chlorine EXCEPT that______.

A．chlorine’s efficacy is affected by sunlight
B．chlorine is made up of two chemicals: hypochlorous acid and hypochlorine ion
C．chlorine is usually said to be malodorous
D．chlorine levels must be routinely assessed in pool water

单项选择题

For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth. Yet, even in the most cloud-free regions of the planet, the solar constant cannot be measured precisely. Gas molecules and dust particles in the atmosphere absorb and scatter sunlight and prevent some wavelengths of the light from ever reaching the ground. With the advent of satellites, however, scientists have finally been able to measure the Sun’s output without being impeded by the Earth’s atmosphere. Solar Max, a satellite from the National Aeronautics and Space Administration(NASA), has been measuring the Sun’s output since February 1980. Although a malfunction in the satellite’s control system limited its observation for a few years, the satellite was repaired in orbit by astronauts from the space shuttle in 1984. Max’s observations indicate that the solar constant is not really constant after all. The satellite’s instruments have detected frequent, small variations in the Sun’s energy output, generally amounting to no more than 0. 05 percent of the Sun’s mean energy output and lasting from a few days to a few weeks. Scientists believe these fluctuations coincide with the appearance and disappearance of large groups of sunspots on the Sun’s disk. Sunspots are relatively dark regions on the Sun’s surface that have strong magnetic fields and a temperature about 2, 000 degrees Fahrenheit cooler than the rest of the Sun’s surface. Particularly large fluctuations in the solar constant have coincided with sightings of large sunspot groups. In 1980, for example, Solar Max’s instruments registered 0. 3 percent drop in the solar energy reaching the Earth. At that time a sunspot group covered about 0. 6 percent of the solar disk, an area 20 times larger than the Earth’s surface. Long-term variations in the solar constant are more difficult to determine. Although Solar Max’s data have indicated a slow and steady decline in the Sun’s output, some scientists have thought that the satellite’s aging detectors might have become less sensitive over the years, thus falsely indicating a drop in the solar constant. This possibility was dismissed, however, by comparing Solar Max’s observations with data from a similar instrument operating on NASA’s Nimbus 7 weather satellite since 1978.Why is it not possible to measure the solar constant accurately without a satellite

A．The Earth is too far from the Sun.
B．Some areas on Earth receive more solar energy than others.
C．There is not enough sunlight during the day.
D．The Earth’s atmosphere interferes with the sunlight.

单项选择题

For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth. Yet, even in the most cloud-free regions of the planet, the solar constant cannot be measured precisely. Gas molecules and dust particles in the atmosphere absorb and scatter sunlight and prevent some wavelengths of the light from ever reaching the ground. With the advent of satellites, however, scientists have finally been able to measure the Sun’s output without being impeded by the Earth’s atmosphere. Solar Max, a satellite from the National Aeronautics and Space Administration(NASA), has been measuring the Sun’s output since February 1980. Although a malfunction in the satellite’s control system limited its observation for a few years, the satellite was repaired in orbit by astronauts from the space shuttle in 1984. Max’s observations indicate that the solar constant is not really constant after all. The satellite’s instruments have detected frequent, small variations in the Sun’s energy output, generally amounting to no more than 0. 05 percent of the Sun’s mean energy output and lasting from a few days to a few weeks. Scientists believe these fluctuations coincide with the appearance and disappearance of large groups of sunspots on the Sun’s disk. Sunspots are relatively dark regions on the Sun’s surface that have strong magnetic fields and a temperature about 2, 000 degrees Fahrenheit cooler than the rest of the Sun’s surface. Particularly large fluctuations in the solar constant have coincided with sightings of large sunspot groups. In 1980, for example, Solar Max’s instruments registered 0. 3 percent drop in the solar energy reaching the Earth. At that time a sunspot group covered about 0. 6 percent of the solar disk, an area 20 times larger than the Earth’s surface. Long-term variations in the solar constant are more difficult to determine. Although Solar Max’s data have indicated a slow and steady decline in the Sun’s output, some scientists have thought that the satellite’s aging detectors might have become less sensitive over the years, thus falsely indicating a drop in the solar constant. This possibility was dismissed, however, by comparing Solar Max’s observations with data from a similar instrument operating on NASA’s Nimbus 7 weather satellite since 1978.Why did scientists think that Solar Max might be giving unreliable information

A．Solar Max did not work for the first few years.
B．Solar Max’s instruments were getting old.
C．The space shuttle could not fix Solar Max’s instruments.
D．Nimbus 7 interfered with Solar Max’s detectors.

单项选择题

For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth. Yet, even in the most cloud-free regions of the planet, the solar constant cannot be measured precisely. Gas molecules and dust particles in the atmosphere absorb and scatter sunlight and prevent some wavelengths of the light from ever reaching the ground. With the advent of satellites, however, scientists have finally been able to measure the Sun’s output without being impeded by the Earth’s atmosphere. Solar Max, a satellite from the National Aeronautics and Space Administration(NASA), has been measuring the Sun’s output since February 1980. Although a malfunction in the satellite’s control system limited its observation for a few years, the satellite was repaired in orbit by astronauts from the space shuttle in 1984. Max’s observations indicate that the solar constant is not really constant after all. The satellite’s instruments have detected frequent, small variations in the Sun’s energy output, generally amounting to no more than 0. 05 percent of the Sun’s mean energy output and lasting from a few days to a few weeks. Scientists believe these fluctuations coincide with the appearance and disappearance of large groups of sunspots on the Sun’s disk. Sunspots are relatively dark regions on the Sun’s surface that have strong magnetic fields and a temperature about 2, 000 degrees Fahrenheit cooler than the rest of the Sun’s surface. Particularly large fluctuations in the solar constant have coincided with sightings of large sunspot groups. In 1980, for example, Solar Max’s instruments registered 0. 3 percent drop in the solar energy reaching the Earth. At that time a sunspot group covered about 0. 6 percent of the solar disk, an area 20 times larger than the Earth’s surface. Long-term variations in the solar constant are more difficult to determine. Although Solar Max’s data have indicated a slow and steady decline in the Sun’s output, some scientists have thought that the satellite’s aging detectors might have become less sensitive over the years, thus falsely indicating a drop in the solar constant. This possibility was dismissed, however, by comparing Solar Max’s observations with data from a similar instrument operating on NASA’s Nimbus 7 weather satellite since 1978.The attempt to describe the solar constant can best be described as______.

A．an ongoing research effort
B．a question that can never be answered
C．an issue that has been resolved
D．historically interesting, but irrelevant to contemporary concerns

单项选择题

For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth. Yet, even in the most cloud-free regions of the planet, the solar constant cannot be measured precisely. Gas molecules and dust particles in the atmosphere absorb and scatter sunlight and prevent some wavelengths of the light from ever reaching the ground. With the advent of satellites, however, scientists have finally been able to measure the Sun’s output without being impeded by the Earth’s atmosphere. Solar Max, a satellite from the National Aeronautics and Space Administration(NASA), has been measuring the Sun’s output since February 1980. Although a malfunction in the satellite’s control system limited its observation for a few years, the satellite was repaired in orbit by astronauts from the space shuttle in 1984. Max’s observations indicate that the solar constant is not really constant after all. The satellite’s instruments have detected frequent, small variations in the Sun’s energy output, generally amounting to no more than 0. 05 percent of the Sun’s mean energy output and lasting from a few days to a few weeks. Scientists believe these fluctuations coincide with the appearance and disappearance of large groups of sunspots on the Sun’s disk. Sunspots are relatively dark regions on the Sun’s surface that have strong magnetic fields and a temperature about 2, 000 degrees Fahrenheit cooler than the rest of the Sun’s surface. Particularly large fluctuations in the solar constant have coincided with sightings of large sunspot groups. In 1980, for example, Solar Max’s instruments registered 0. 3 percent drop in the solar energy reaching the Earth. At that time a sunspot group covered about 0. 6 percent of the solar disk, an area 20 times larger than the Earth’s surface. Long-term variations in the solar constant are more difficult to determine. Although Solar Max’s data have indicated a slow and steady decline in the Sun’s output, some scientists have thought that the satellite’s aging detectors might have become less sensitive over the years, thus falsely indicating a drop in the solar constant. This possibility was dismissed, however, by comparing Solar Max’s observations with data from a similar instrument operating on NASA’s Nimbus 7 weather satellite since 1978.What does this passage mainly discuss

A．The components of the Earth’s atmosphere.
B．The launching of a weather satellite.
C．The measurement of variations in the solar constant.
D．The interaction of sunlight and air pollution.

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