單項(xiàng)選擇題

A hydrostatic release mechanism for a liferaft（）.

A.must be wet before it will release
B.should be kept in a watertight cover except in an emergency
C.will inflate the raft in its cradle if operated manually
D.must be submerged to a certain depth to release automatically

微信掃碼免費(fèi)搜題