单项选择题
The phrase when built in the certificate of vessel’s nationality definitely means（）.
A.when was your vessel built B.at what time is your vessel building C.when is your vessel built D.at what time you built your vessel
单项选择题 The port in which crew or passengers go on board the ship is called（）.
单项选择题 The principal purpose of adjustment of the magnetic compass is to eliminate（）as far as possible.
单项选择题 The routing system which aimed at reducing the risk of casualties is called as（）.
