单项选择题
A.not under command
B.restricted in her ability to maneuver
C.engaged in towing
D.fishing
单项选择题 If your vessel is underway in fog and you hear one prolonged and three short blasts，this is a （）.
单项选择题 If there is sufficient sea room，alteration of（）may be the most effective action to avoid close-quarters situation.
单项选择题 If there is any doubt as to the proper operation of a radar，which statement is TRUE?（）.