单项选择题
A.MAYDAY sent by radiotelephone B.Continuous sounding of fog horn C.Green star shells fired from a launcher D.Square flag and ball in a vertical line
When two vessels are in immediate danger of collision，t...
单项选择题When two vessels are in immediate danger of collision，the stand-on vessel must（）.
A.abandon ship B.assist in taking whatever action is necessary to avoid collision C.hold course and speed D.sound a distress signal
