---Are you satisfied with what the captain explained?
---Not at all. It couldn’t have been________.
| A．so bad | B．worse | C．the worst | D．the best |
In order not to be _________, I spoke in a man’s voice on the phone.
| A．realized | B．recommended | C．requested | D．recognized |
Ladies and gentlemen, please fasten your seat belts. The plane _________.
| A．is taking off | B．takes off | C．has taken off | D．will be taken off |
Stephen Hawking believes that the earth is unlikely to be the only planet _life has developed gradually.
| A．that | B．where | C．which | D．whose |
---- An ant has two stomachs --- one for itself and the other for others.
----Really? Quite interesting. I ________ anything about it.
| A．don’t know | B．hadn’t known | C．haven’t known | D．didn’t know |
Scientists say it may be one year or so ________ it is possible to test the new medicine on human patients.
| A．when | B．after | C．before | D．since |