—This wall of air is an effective answer to the problem and it ____ work.
—But it is a question to put such a wall of air around the statue.
| A．may | B．must | C．should | D．could |
They had no sooner arrived at the bus station than the bus .
| A．had left | B．will leave | C．left | D．is leaving |
On world AIDS Day, the minister of Health Department demanded that the problems______paid special attention.
| A．referred to being | B．referred to be | C．refer to being | D．refer to be |
We must apply our minds to ________a solution.
| A．find | B．finding | C．found | D．being found |
______in the regulation is that you should not tell other people the password of your e-mail account.
| A．What is required | B．What requires | C．It is required | D．It requires |
It is ____the ancient temple at the top of the mountain.
| A．worth to visit | B．worthwhile visit |
| C．worthwhile visiting | D．worthy being visited |