单项选择题
Whenever your marine radio is on，FCC Rules require you to monitor（）.
A.a commercial ship-to-ship channel B.the last frequency that was used C.the distress and calling frequency D.the radio only if expecting a call
单项选择题 When you are firing a pyrotechnic distress signal，it should be aimed（）.
单项选择题 When two vessels are in immediate danger of collision，the stand-on vessel must（）.
单项选择题 What is NOT a distress signal?（）
