单项选择题
A.to the top to expel all vapors from the tanks
B.to the top so the operator is certain how much fuel he has aboard
C.with only sufficient fuel for the planned trip so excess gasoline is not carried
D.to near the top with some space allowed for gasoline expansion
单项选择题 Gasoline fumes tend to（）.
单项选择题 Each ship having an inert gas system must have a portable instruments to measure concentrations of hydrocarbon vapor in inert atmospheres and also to measure（）.
单项选择题 Each inert gas system must be designed to supply the cargo tanks with a gas，or mixture of gasses，that has an oxygen content by volume of（）.