The major refueling hazard is the possible _______ of the fuel by a spark that causes fumes to ignite.
A.condensation
B.combustion
C.contamination
D.leakage
正确答案是B
The major refueling hazard is the possible _______ of the fuel by a spark that causes fumes to ignite.
A.condensation
B.combustion
C.contamination
D.leakage
正确答案是B