47 Since people have ignored warnings about global warming for more than 20 years, they have to suffer its now
=> Having ignored warnings about global warming for more than 20 years, people have to suffer its now
49. Students in High School had taken an active part in the Green Summer activities. They were rewarded for that
=> Students were rewarded for having taken an active part in the Green Summer activities
50. We hadn't driven on the left of the streets in England. We were heavily fined for that.
=> We were heavily fined for not having driven on the left of the streets in England
48 This factory had dumped tons of rubbish into the sea. The factory denied it
=> The factory denied having dumped tons of rubbish into the sea.
46. After he talked to the professor, he changed his attitude to envirnment.
=>  Having talked to the professor, he changed his attitude to envirnment.

26. There are many ways for us to solve the .... issue in order to save our environment
A disasters
B. fossil fuels
C. global warming
D gases
30.The number and types of plants and animals existing in a particular area or in the world is called......
A. Catastrophy
B disaster
C. Biodiversity
D. Extinction
31.The main cause of the current global warming trend is the greenhouse .....
A causes
B.solutions
C. gas
D. damage