单项选择题
Chafing gear is normally used（）.
A.for portable fenders B.for ground tackle C.on the inside of the hawsepipe D.on mooring lines
单项选择题 Back-up wires on a towed vessel provide（）.
单项选择题 At the instant when a string of casing being run from a ship is landed in the well head,（）.
单项选择题 Anchor shackles should have a breaking strength that is（）.
