单项选择题
The central longitudinal structural hull strength member of the lower hulls of semisubmersible ship’s is called the（）.
A.stress plate B.keel C.rider plate D.main beam
单项选择题 Support of ship side plating is provided primarily by transverse（）.
单项选择题 Structural stress on a ship can be reduced by（）.
单项选择题 Structural stress levels in a ship are the sum of loading stresses and stresses due to（）.
