Ladies and gentlemen, please fasten your seat belts. The plane ________.
| A．takes off | B．is taking off | C．has taken off | D．took off |
This book is worth _____.
| A．to read it | B．reading it | C．reading | D．to read |
We should do ___ the teacher told us.
| A．because | B．like | C．as | D．since |
The number of the people in the world ______ growing faster and faster.
A. is b. are C. have D. were
I’m sorry to have kept you ________ for a long time.
A. wait b. to wait c. waiting D. to be waiting
The film __________ for ten minutes when we got to the cinema.
| A． had already been on | B．had already begun |
| C．have already been on | D．have already begun |