单项选择题
A.when two stations communicate with each other B.in any radio system and at any time C.when one ship sends a message to another station D.for communication among some stations
It is required that ships proceeding at sea should keep...
单项选择题It is required that ships proceeding at sea should keep continuous watch on（）.
A.VHF channels 16 and 13 B.Appropriate DSC distress and safety frequencies C.INMARSAT TDM message channel D.VHF channel 70 and channel 8
General radio communications in the global system are t...
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
why do some stations keep silence?（）A.Because they are ...
单项选择题why do some stations keep silence?（）
A.Because they are not engaged in the distress traffic B.they will affect the transmission of the distress traffic C.The powers of these stations are very weak D.They are not in charge of search and rescue
