液体表面的蒸汽与空气形成可燃气体，遇到点火源时，发生一闪即灭的现象称为（）。
A.爆炸
B.蒸发
C.闪燃
参考答案：C
Hardly ____ the airport when the plane took off. [ ]
A. I had arrived at
B. had I arrived
C. had I reached
D. I had got to
工程咨询方法中的基础方法是（）。
A.逻辑框架法
B.对比法
C.系统分析法
D.综合评价法
