单项选择题
A wooden float placed between a ship and a dock to prevent damage to both is called a（）.
A.camel B.dolphin C.rat guard D.wedge
单项选择题 A term applied to the bottom shell plating in a double-bottom ship is（）.
单项选择题 A strong back refers to a（）.
单项选择题 A spreader bar is used to（）.
