单项选择题
A.only when there is positive stability
B.only when there is negative stability
C.only when there is neutral stability
D.at all times
单项选择题 The amount of freeboard which a ship possesses has a tremendous effect on its（）.
单项选择题 Load line regulations are designed to insure that a vessel has adequate structural strength and sufficient（）.
单项选择题 In the absence of external forces，the center of gravity of a floating vessel is located directly above the（）.