单项选择题
A.causing moisture to accumulate against the bulkhead
B.lowering the vapor pressure of the commodity
C.lowering the dew point of the air
D.raising the vapor pressure of the commodity
单项选择题 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（）.
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.