Task 1:

1. e

2. a

3. b

4. i

5. d

6. c

7. g

8. j

9. h

10. f

Task 2:

1. better

2. worst

3. further

4. most disgusting

5. luckier

4.  Several environmental issues were listed by Leonardo DiCaprio in his Earth Day speech. 

5. Too much freshwater is being used nowadays.

6. Chemicals are being overused by some farmers in their crops.

7. Too much oil was being consumed by Europe when ...

8. Endangered species were being saved after the oil spill by the environmentalists.

9. The rise of temperature has been caused in many areas by climate change.

10.  Some rainforest ecosystems have been destroyed by deforestation.

11. The hydrogen technology hadn't still invented in the 19th century.

12. Specific regions will be affected in different ways by global warming.

13. The world economy would be improved if there was the discovery of ... car.

14. Serious threats can be posed by genetic engineering.

15. All household waste should be separated.

16. Toxic chemicals shouldn't be dumped into rivers and lakes.

17. Chemical discharges might be decreased by factories if they wanted.

18. All our drinking water is going to be contaminated by pollution.

19. Many economic and environmental problems are going to be solved by a hybrid... car.