单项选择题
A sheave is a（）.
A.grooved wheel in a block B.line to hold a lifeboat next to the embarkation deck C.partial load of grain D.seaman's knife
单项选择题 A sea anchor is（）.
单项选择题 A person referring to the stern sheets of a lifeboat is speaking of（）.
单项选择题 （）is used for heaving up and slacking away the anchor and chain.
