单项选择题
Vessels are required to illuminate their（）to aid identification.
A.funnels B.tunnels C.channels D.handles
单项选择题 Vessels ramaining（）a few hours should moor with anchors.
单项选择题 Vessels should be manned（）duly qualified officers and crew adequate（）ensure the safety of navigation.
单项选择题 VHF radio is one of the very important navigational instruments on board,（）messages can be sent.
