21. Solar energy can help people ......................the earth’s resources.
A. recycle B. conserve C. reuse D. volunteer
22. There are 40 students in this class. There are 20 school boys . They .................50%
A. go on B. look for C. account for D. place
23. They turned on the fans ......................it was hot.
A. so B. as C. but D. however
24. Today we have Math, History, English ...................Chemistry.
A. or B. and C. but D. therefore
25. We can .............an ordinary 100 watt light bulb with an energy-saving bulb to save electricity.
A. heat B. install C. store D. replace
26. I am .......................that people have spoiled this area.
A. disappoint B. diapponting C. disappinted D. to disappoint
27. There’s nothing good on TV. Why don’t you turn it .................?
A. on B. off C. down D. up
28. We should ………..energy by turning off all the lights when they aren’t necessary.
A. waste B. save C. minimize D. prohibit
29. .......................many households use energy-saving lights bulbs, their electricity bill is still enormous.
A. Since B. Although C. When D. If
30. If you ……………talking in class, you ‘ll be punished.
A. turn on B. look after C. take off D. go on
31. They have to pay a big water bill ……...………they let the faucets drip freely.
A. because B. so C. and D. however
32. He suggested ……………..the gas bill on time.
A. paying B. she should pay C. that she should pay. D. A,B,C are correct