单项选择题
A.If B.Whenever C.Because D.Where
Before（）, a station shall take precautions to ensure th...
单项选择题Before（）, a station shall take precautions to ensure that its emission will not interfere with transmission already in progress.
A.transmit B.to transmitting C.transmitting D.in transmitting
Two vessels（）while they re sailing in Huangpu River.A.s...
单项选择题Two vessels（）while they „re sailing in Huangpu River.
A.strike B.strikes C.are striking D.struck
（）all ships in a large sea area being alerted, an “area...
单项选择题（）all ships in a large sea area being alerted, an “area call” will normally be transmitted so that only those ships in the vicinity of the distress incident are alerted.
A.Avoiding B.To be avoided C.Avoided D.To avoid
