单项选择题
Signals for locating will be transmitted in the 9GHz band by means of（）.
A.SART B.DSC C.NBDP D.RT
单项选择题 A ship station on receiving a shore-to-ship distress alert should（）.
单项选择题 What channel is general communication used?（）
单项选择题 General communications are those communications（）.
