单项选择题
If the buoyant force on a ship’s hull is equal to the displacement tonnage，the ship will（）.
A.require ballast B.be down by the head C.sink D.float
单项选择题 For an upright vessel，draft is the vertical distance between the keel and the（）.
单项选择题 For a floating vessel，true mean draft is always the（）.
单项选择题 Deballasting a double bottom has what affect on KG?（）
