Question

Mary was caught in a traffic jam and by the time she arrived at the airport her father’s plane______.

1. A.
   took off
2. B.
   had already taken off
3. C.
   was take off
4. D.
   had already been taken off

Answer 1

B
by the time与she arrived这一过去的动作连用，表示到过去那时为止已经完成的动作，用过去完成时。take off指“起飞”，没有被动语态。