单项选择题
A.Fire a red flare at night or a red smoke signal by day
B.Send the Morse signal "N" by flashing light
C.Make a round turn (360°) and resume course
D.Make an "S" turn (hard right then hard left) and resume course
单项选择题 All self-propelled vessels on an international voyage must be equipped with how many Emergency Position Indicating Radio beacons (EPIRB)? （）
单项选择题 After having activated the emergency position indicating radio beacon，you should（）.
单项选择题 After an explosion，repair of emergency machinery and services should be accomplished（）.