单项选择题
A.the gasoline tank is full
B.the bilges，cabins，etc. are thoroughly ventilated
C.you have fresh water on board
D.Each of the above is followed
单项选择题 Before entering a tank，always check the vapor content（）a combustible gas indicator.
单项选择题 After the initial cleaning of flue gas in an inert gas system the gas is passed through what device for final cleaning?（）.
单项选择题 According to the regulations，to prevent excessive pressure buildup in cargo tanks containing LFG，they are fitted with（）.