单项选择题
The end of the joint with the exterior threads is called the（）.
A.pin B.stem C.box D.stand
单项选择题 The document on a vessel，annually endorsed by an American Bureau of Shipping surveyor，is called the（）.
单项选择题 The conclusion is（）the said ship is fit to continue to sail.
单项选择题 The burden of proving unseaworthiness is upon those who（）it.
