在实际生产中，以（）的含氧良定作烃和空气混合气体绝不燃烧的临界点
A.6%
B.8%
C.10%
D.12%
参考答案：B
You'd better take something to read when you go to see the doctor ________ you have to wait. [ ]
A. even if
B. as if
C. in case
D. in order that
