单项选择题
A.keeping the fuel tanks topped off
B.increasing the free surface effect
C.keeping the fuel tanks at least half MI
D.keeping at least one fuel tank empty for slops
单项选择题 When reentering an engine room that has been flooded with CO2, the investigating team should initially（）.
单项选择题 If there has been a fire in a closed unventilated compartment it may be unsafe to enter because of （）.
单项选择题 After a fire has been extinguished in a closed space, personnel may safely enter the space when （）.