单项选择题
A sweep oar is an oar that is（）.
A.generally shorter than the others and is used to steer with B.is longer than the others and is used as the stroke oar C.is raised in the bow of the boat for the steersman to steer by D.longer than the others used for steering
单项选择题 A person who sees someone fall overboard should（）.
单项选择题 A man aboard a vessel，signaling by raising and lowering his outstretched arms to each side，is indicating（）.
单项选择题 A flooded lifeboat on board a vessel would adversely affect the vessel’s stability by（）.
