单项选择题
A block and tackle is rove to advantage. This means that the（）.
A.blocks have been overhauled B.hauling parts of two tackles are attached C.hauling part leads through the movable block D.hauling part leads through the standing block
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?（）
单项选择题 Limber is a term associated with（）.
