What will people die of in 100 years? If you think that is a simple question, you ______ attention to the revolution taking place in biotechnology．
| A．have not been paying | B．had not been paying |
| C．were not paying | D．will not be paying |
Old-fashioned phones matter when wireless networks __________ in disasters.
| A．break out | B．break up |
| C．break in | D．break down |
The streets are all dry. It _____ during the night.
| A．must have rained | B．should have rained |
| C．can’t have rained | D．couldn’t rain |
I would have gone to my cousin’s birthday party last night, but I was not.
| A．available | B．accessible |
| C．acceptable | D．adequate |
--I am sure Mary will win the first place in the coming competition.
--I think so. She ________ for it for months.
| A．has prepared | B．has been preparing |
| C．had prepared | D．prepared |
There is _____ Liu Chang in our class, but I’m afraid he isn’t ____ one you want.
| A．the, a | B．a, the |
| C．a, / | D．the, the |