The producer comes regularly to collect the cameras _______ to our shop for quality problems.
| A．returning | B．returned | C．to return | D．to be returned |
We work together to achieve our common purpose: ____ world that is safer, cleaner and healthier than ____ one we founded.
| A．the; the | B．a; 不填 | C．a; the | D．the; 不填 |
— Are you pleased with what he has done?
— It couldn’t be____. Why didn’t he put more effort into his work?
| A．any worse | B．much better | C．so bad | D．best |
Because of the heavy snow, we had to delay the visit until this weekend to the artgallery ____ in the center of our city these days.
| A．being held | B．holding | C．to be held | D．held |
While watching television, ____.
| A．the doorbell rang | B．we heard the doorbell ring |
| C．there was someone knocking at the door | D．the doorbell was ringing |
I’ll have all of the readings ____ by the end of this term if my plan goes well.
| A．completing | B．to complete | C．completed | D．being completed |