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 is（）.
单项选择题 A stay is（）.
单项选择题 A splice that can be used in running rigging，where the line will pass through blocks，is a（）.
