单项选择题
A.vertically above the center of buoyancy
B.vertically above the center of gravity
C.at the intersection of the upright vertical centerline and the line of action of the buoyant force
D.at the geometric center of the underwater volume
单项选择题 As a ship moves through the water，it causes a wake，which is also moving forward relative to the sea. In addition to a fore and aft motion，this wake also has a(n)（）.
单项选择题 Angular motion about the vertical axis of a vessel is called（）.
单项选择题 Angular motion about the longitudinal axis of a vessel is known as（）.