— What should we do to prevent the flu?
—We should keep our rooms_____ and the air fresh all the time.
A. cleaning B. cleaned C. clean
Albert! It’s time for you to go to bed, _________ you will feel tired tomorrow.
| A．or | B．but | C．so | D．and |
While my brother _______ football with his friends yesterday, my sister _______ her homework.
| A．was playing; did | B．played; was doing |
| C．was playing; was doing | D．played; did |
—Excuse me, sir, smoking _________ in the gas station.
— Oh, I’m really sorry.
| A．doesn’t allow | B．isn’t allowed |
| C．aren’t allowed | D．wasn’t allowed |
Mr. Green with his sons and daughters often _________ a walk in the park after supper.
| A．take | B．takes |
| C．took | D．are taking |
The _________ careful you are, the _________ mistakes you will make.
| A．more; more | B．more; less |
| C．less; fewer | D．more; fewer |