单项选择题
An example of a messenger is a（）.
A.fairlead B.heaving line C.stay D.warp
单项选择题 An inflatable life raft can be launched by（）.
单项选择题 An inflatable life raft is hand-launched by（）.
单项选择题 An inflation life raft is thrown into the water from a sinking vessel, what occurs automatically after the painter trips the C02 bottles to inflate the raft?（）.
