单项选择题
A life line must be conncted to the life raft（）.
A.at the bow B.at the stern C.in the middle D.all around
单项选择题 A life raft which has inflated bottom-up on the water（）.
单项选择题 A load line of a ship is assigned by the（）.
单项选择题 A new coil of nylon line should be opened by（）.
