单项选择题
A “strongback” refers to a（）.
A.bar securing a cargo port B.centerline vertical bulkhead C.deep beam D.spanner stay
单项选择题 A “dangerous cargo manifest” is needed for you to carry a combustible cargo. You should obtain the shipping papers to make this “manifest” from the（）.
单项选择题 A“chock” is a（）.
单项选择题 （）is known as a long hatch during loading operation．
