单项选择题
0il product samples should be taken from the（）.
A.dock riser B.ships cargo tanks C.shore tank discharge D.All of the above
单项选择题 0n a single-screw vessel the stern frame（）.
单项选择题 0n a vesel proceeding from a very cold to a warm climate with a cargo of a nonhygroscopic nature in the holds, which is true?（）.
单项选择题 0n a vessel, the keel is the primary strength member of the lower hull form in which direction?（）.
