Em còn 7 câu này ạ, mong mọi người giúp đỡ, em cảm ơn ạ 21. David was rewarded………..having taken an active part in the Green Summer activities. A. of B. about C. for D. with 22. …………they have used up the fossil fuel resourses in their country, they have to find some types of alternative energy. A. Although B. Since C. Because of D. Despite 23. After they indentified the causes of global warming, they worked out………to reduce its effects. A. solutions B. causes C. effects D. influences 24. Global warming is one of the biggest issues…………humans nowadays. A. faced B. facing C. to face D. to be faced 25. The result of ………..studies show that global warming is real. A. numeral B. numerical C. number D. numerous 26. Having been informed about the bad effects of chemical fertilisers, the farmers……….using them sparingly on their farms. A. start B. are started C. started D.had started 27. The factory was heavily fined for …………..tons of toxic waste into the river. A.having dumped B. dumped C. to be dumped D. to dumped 28. In the USA, about 40% of CO2 emissions …………electricity production. A. come across B. come from C. come about D. come out