单项选择题
A.is found in the hydrostatic tables for a level vessel
B.multiplied by the displacement yields the righting moment
C.is always positive
D.is calculated by subtracting KG from KM
单项选择题 In small-angle stability，when external forces exist，the buoyant force is assumed to act vertically upwards through the center of buoyancy and through the（）.
单项选择题 In the presence of external forces，the center of buoyancy of an inclined vessel is vertically aligned with the（）.
单项选择题 Increasing free surfaces has the effect of raising the（）.