单项选择题
Aboard ship，vertical flat plates running transversely and connecting the vertical keel to the margin plates are called（）.
A.floors B.intercostals C.girders D.stringers
单项选择题 A wooden float placed between a ship and a dock to prevent damage to both is called a（）.
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（）.
