1. When I ___________ the knock, I ______ the door.
A. was hearing/ opened B. heard/ opened
C. was hearing/ was opening D. heard/ have opened
2. He ______ able to drive since he had an accident 5 years ago .
A. has not been B. will not be
C. had not been D. would not be
3. We __ for months before we reached an island
.A. have been sailing B. had been sailing
C. would be sailing D. were sailing
4. They ____ the trip until we come.
A. will start B. didn’t start C. started D. won’t start
giúp em vs ạ
