单项选择题
A check line is（）.
A.A safety line attached to a man working over the side B.Used to measure water depth C.Used to slow the headway of a barge D.Used to measure the overhead height of a bridge
单项选择题 A（）is the intersection of the surface of a sphere and a plane passing through the center of the sphere.
单项选择题 A “Mediterranean moor” should be used when（）.
单项选择题 （）is not a step for anchoring preparation.
