单项选择题
One method of reducing the length of radio transmissions without distorting the meaning of your words is by using（）.
A.slang B.secret codes C.procedure words D.analogies
单项选择题 On which vessels is GMDSS required? （）
单项选择题 If your vessel is equipped with a radiotelephone，what must also be aboard?（）
单项选择题 If a GMDSS radio operator initiates a DSC distress transmission but does not insert a message，what happens? （）
