单项选择题
The locking pin that joins the parts of a detachable link is held in position by（）.
A.a tack weld B.the self-locking characteristics of its taper C.a cotter pin D.a lead plug
单项选择题 The lifeline of a life float or buoyant apparatusshall（）.
单项选择题 The lay of a line refers to（）.
单项选择题 The grooved wheel inside a block is called a（）.
