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（）.
A.center of gravity B.center of flotation C.metacenter D.metacentric height
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（）.
单项选择题 Increasing the number of slack liquid tanks has the effect of raising the（）.
