The radar control used to reduce sea return at close ranges is the（）.

单项选择题The radar control that shortens all echoes on the display and reduces clutter caused by rain or snow is the（）.

A.sensitivity time control (sea clutter control)
B.receiver gain control
C.brilliance control
D.fast time constant (differentiator)

单项选择题The radar control that reduces weak echoes out to a limited distance from the ship is the（）.

A.sensitivity time control (sea-clutter control)
B.receiver gain control
C.brilliance control
D.fast time constant (differentiator)

单项选择题The officer of the watch should use radar when appropriate and at all times in（）waters.

A.congesting
B.congested
C.congestion
D.congest

单项选择题The fitting of an efficient radar reflector is likely to considerably increase the ship’s probability of（）.

A.detection
B.being detected
C.the detective
D.the detected

单项选择题The description Racon beside an illustration on a chart would mean a（）.

A.radar transponder beacon
B.radar conspicuous beacon
C.radar calibration beacon
D.circular radiobeacon