单项选择题
A tackle by which the outer end of a boom is raised and lowered is the topping（）.
A.boom B.lift C.raise D.tackle
单项选择题 A stopper used in securing the ground tackle for sea that consists of a grab attached to a turnbuckle is a（）.
单项选择题 A splice that can be used in running rigging，where the line will pass through blocks，is a（）.
单项选择题 A snatch block would most likely be used as a（）.
