单项选择题
A boom vang（）.
A.holds the boom down and flattens the main sail B.draws the head of the sail to windward C.tautens the standing rigging D.douses the gaff topsail
单项选择题 A bluff bar is a bar（）.
单项选择题 A block and tackle is rove to advantage. This means that the（）.
单项选择题 A bilge suction line，in a fishing vessel with more than 16 individuals aboard，must have a strainer with an open area not less than how many times the open area of the suction line?（）
