航海英语航海仪器使用说明书章节练习(2018.02.12)

单项选择题
Magnetic heading differs from compass heading by（）.
A.compass error
B.true heading
C.variation
D.deviation
单项选择题
（）the canal transit，the radar was operating.
A.At
B.In
C.During
D.With
单项选择题
The microsecond unit of time is used in radar applications. The microsecond represents which of the following?（）.
A.one-millionth part of a second
B.one-thousandth part of a second
C.one-hundredth part of a second
D.one-tenth part of a second
单项选择题
My gyro-compass（）is two degrees east.
A.trouble
B.error
C.wrong
D.mistake
单项选择题
（）20 targets can be tracked at one time．When maximum tracking capacity is reached，no further acquisitions are possible.
A.As many as
B.So many as
C.As much as
D.As more as
单项选择题
The transmission time duration of a single pulse of radio-frequency energy is a function of the（）.
A.persistence
B.pulse repetition rate
C.pulse length
D.resolution
单项选择题
A radar display in which North is always at the top of the screen is a(n)（）.
A.unstabilized display
B.stabilized display
C.composition display
D.relative display
单项选择题
Deviation is the angle between the（）.
A.true meridian and the axis of the compass card
B.true meridian and the magnetic meridian
C.magnetic meridian and the axis of the compass card
D.axis of the compass card and the degaussing meridian
单项选择题
An indirect radar echo is caused by a reflection of the main lobe of the radar beam off the observer’s vessel. Which of the following is NOT a characteristic of indirect echoes?（）.
A.Their bearing is almost constant，even when the true bearing of the contact changes appreciably
B.They always appear on a bearing of 90°from the true bearing of the contact
C.The indirect echoes usually appear in shadow sectors
D.When plotted，their movements are usually abnormal
单项选择题
The radar component that generates the radio-frequency energy in the form of short powerful pulses is which of the following?（）.
A.magnetron
B.receiver
C.indicator
D.modulator