单项选择题
Freeing ports on a vessel with soild bulwards（）.
A.prevent stress concentration in the bulwark B.permit easy jettison of deck cargo in an emergency C.provide opening through the bulwarks for mooring lines D.allow water shipped on deck to flow off rapidly
单项选择题 Fuel oil tank vents are fitted with a screen which will stop（）.
单项选择题 Functions aboard a tanker or tank barge such as connecting, disconnecting, and topping off must be supervised by（）.
单项选择题 Gasoline tanks should be filled（）.
