It is when the plane ______ that you’d better find out at the booking office.

    A. would take off           B. had taken off

    C. was taking off           D. is taking off

It is when the plane ______ that you’d better find out at the booking office.

1. A.
   would take off
2. B.
   had taken off
3. C.
   was taking off
4. D.
   is taking off