单项选择题
General radio communications in the global system are those between（）concerning the management and operation of the ships and may have impact on their safety.
A.SAR party and the ship in distress B.SAR authorities and the ship in distress and survival craft C.A ship station and any coast station D.Ship stations and shore-based communication network
单项选择题 why do some stations keep silence?（）
单项选择题 What channel is general communication used?（）
单项选择题 What’s the advantage when using the satellites?（）
