单项选择题
A vessel showing a yellow light over a white light at night is a vessel（）.
A.engaged in piloting B.towing astern C.engaged in fishing D.in distress
单项选择题 A message warning of a tropical storm should be sent as a(n)（）.
单项选择题 A crew member has just fallen overboard off your port side. Which action should you take?（）.
单项选择题 （）of the following messages is allowed to be transmitted on the radiotelephone without the authority of the Master.
