1. Don't come before six o'clock. I will be busy.
B. before
2. It is necessary that Mike should ask everybody present for permission to smoke before lighting a cigarette.
D. for/before
3. You need a lot of experience in order to do this job.
C. in order to
1. B. before
2. D. for/before
3. C.in order to
Объяснение: