单项选择题
The difference between the initial trim and the trim after loading is known as（）.
A.trim B.change of trim C.final trim D.change of draft
单项选择题 The controlling depth of the river is（）.
单项选择题 The center of volume of the immersed portion of the hull is called the（）.
单项选择题 The center of the underwater volume of a floating vessel is the（）.
