单项选择题
The SART should provide a（）indication of its correct operation and should also inform survivors when it is interrogated by radar.
A.sight or sound B.seeing or sounding C.visual or audible D.seeing or hearing
单项选择题 The ARQ mode should be applied（）.
单项选择题 Signals for locating will be transmitted in the 9GHz band by means of（）.
单项选择题 A ship station on receiving a shore-to-ship distress alert should（）.
