Teachers recommend parents_____their children under 12 to ride bicycles to school for safety.
| A．not allow | B．do not allow |
| C．mustn’t allow | D．couldn’t allow |
A good idea __________ to me，
and I quickly picked up the phone to tell Jack about it.
| A．struck |
| B．appeared |
| C．happened |
| D．occurred |
So suddenly __________ that people had no time to escape.
| A．did the big fire happen |
| B．the big fire happened |
| C．was the big fire happened |
| D．the big fire was happened |
I happened __________ with him when he was hit by a stone.
| A．I was talking |
| B．talking |
| C．to talk |
| D．to be talking |
You'd better not phone me between two and six o'clock this afternoon; I __________ a speech then.
| A．will give |
| B．will have been giving |
| C．will be giving |
| D．will have given |
By the middle of the 21st century, the vast majority of the world's population __________ in cities rather than in the country.
| A．are living |
| B．will be living |
| C．have lived |
| D．will have lived |