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.
单项选择题 The fitting of an efficient radar reflector is likely to considerably increase the ship’s probability of（）.
单项选择题 The description Racon beside an illustration on a chart would mean a（）.
