—How long do you think it will be______ man can finally solve the problem of cancer?
—Well，it depends
| A．when | B．until | C．after | D．before |
The soil is becoming poor because farmers here mostly use only one kind of chemical fertilizer for several years________.
| A．in a row | B．on a large scale |
| C．at random | D．to a degree |
With the city ________ clouded by dirty smog, the government has planned to shut down the four major coal-fired power plants.
| A．abruptly | B．frequently |
| C．occasionally | D．regularly |
The IOC Evaluation Commission has come to a ________ conclusion that Beijing is capable of hosting a successful 2022 winter Olympics.
| A．tentative | B．virtual |
| C．definite | D．subtle |
Tom is so creative a person that he always has lots of ________ ideas in his mind, and sometimes we don’t even know what he is thinking about.
| A．novel | B．complex | C．messy | D．absurd |
He is busy writing the article all the morning, only ________ occasionally to have a cup of coffee.
| A．breaking off | B．breaking down |
| C．breaking through | D．breaking up |