单项选择题
0n a vessel, the keel is the primary strength member of the lower hull form in which direction?（）.
A.transverse B.disagonal C.longitudinal D.vertical
单项选择题 0n the fully containerized ship, approximately one-third or more of the cargo is on deck above the rolling center. Top stowed containers are subject to（）.
单项选择题 0ne function of a hulwark is to（）.
单项选择题 0ne of the principal dangers inherent in liquified petroleum gas is（）.
