For some time the expert __________ people of the health risks caused by passive smoking. He says he won't stop until all the smokers around him decide to quit smoking.
| A．is warned | B．is warning | C．has been warning | D．has been warned |
I can’t find my English book. I must ___ it at home this morning.
| A．forget | B．leave | C．have forgotten | D．have left |
--Who did you ___ in the street last Sunday?---Lin Tao, a good friend of mine.
| A．run away | B．run for | C．run into | D．run after |
Something ___ to save our earth. Do you think so?
| A．can do | B．must do | C．has to do | D．must be done |
I’ m sorry, I mistook you ___ your sister ___ mistake.
| A．for, by | B．by, for | C．by, by | D．for, for |
The scientists are trying to ___ natural energy to decrease air pollution.
| A．make friends with | B．make full use of | C．make notes of | D．make into |