A continuous watertight bulkhead is normally also a(n)（）.

单项选择题A band or collar on the top end of a boom to which the topping lift，midships guy，and outboard guys are secured，is called the（）.

A.collar band
B.guy band
C.pad eye collar
D.spider band

单项选择题（）is the main center-line structural member，running fore and aft along the bottom of a ship，sometimes referred to as the backbone.

A.Frame
B.Deckbeam
C.Stringer
D.Keel