单项选择题 The disinfection of various compartments in a vessel by filling with a gaseous agent to destroy rats and all insects pests which act as germ carriers means（）.

单项选择题 The correction to KG for longitudinal free surface effects for a vessel can be found by dividing the vessel’s displacement into the（）.

单项选择题 The center of gravity of a freely swinging load suspended from a pedestal crane acts as if it were located at the（）.