单项选择题
A.exchange navigational information between vessels
B.exchange navigational information between a vessel and a shore station
C.conduct necessary tests
D.exchange operating schedules with company dispatcher
单项选择题 All VHF marine band radios operate in the simplex mode，which means that（）.
单项选择题 A mark or place at which a vessel comes under obligatory entry，transit，or escort procedure is know as（）.
单项选择题 A call between any two ship stations on an intership working frequency shall have a maximum duration of（）.