单项选择题
A.Only when there is a chance of their being seen by rescue vessels
B.At half-hour intervals
C.At one-hour intervals
D.Immediately upon abandoning the vessel
单项选择题 When launching a lifeboat，the tricing pennants should be released（）.
单项选择题 When landing a lifeboat through heavy surf with a strong current running parallel to the beach (from right to left when facing from seaward) the recommended procedure is to（）.
单项选择题 When a man who has fallen overboard is being picked up by a lifeboat，the boat should approach with the wind（）.