单项选择题
A.power ventilation
B.gooseneck vents and flame screens
C.at least two ducts extending to the weather deck
D.a vent header system
单项选择题 Regulations require that cargo tanks carrying grades D or E liquids on tank barges be vented with（）.
单项选择题 Regulations require that cargo pumps in tankers carrying grade D liquid cargo shall be isolatedfrom sources of vapor ignition by（）.
单项选择题 Regulations require that cargo pumprooms on tank barges (constructed in 1965) carrying grades B or C liquid cargoes have power ventilation systems which can completely change the air in （）.