单项选择题
The principal action in changing from transit to survival draft in the event heavy weather threatens is（）.
A.ballasting B.deballasting C.disconnecting D.hanging off
单项选择题 The preferred method of controlling external bleeding is by（）.
单项选择题 The pitch of a propeller is a measure of the（）.
单项选择题 The main reason a long towline is used during an oceantow is that（）.
