20. D

Dẫn chứng: This attitude bothered Gaylord Nelson, who was a senator in the US government, and he had an idea.

21. C

Dẫn chứng: In my town, last Saturday afternoon, lots of people rode their bikes from the park around the town together and back to the park, taking as much time as they could, so that the cars had to wait. Then they talked to all the drivers in cars which just had one person in them, to explain how wasteful that is and how much pollution it causes.

In other places, people collected plastic bags for a week and then made a pile of them in the town square.

22. B

save: cứu, bảo vệ

protect: bảo vệ

23. B

Dẫn chứng: We celebrated Earth Day in my city last week. The idea of this special day began in the 1960s when life was very different. The first Earth Day was just in the United States but on April 22nd, it led to events every year all around the world.

24. A

Dẫn chứng: In my town, last Saturday afternoon, lots of people rode their bikes from the park around the town together and back to the park, taking as much time as they could....You can do anything as long as it makes people of all ages join for a few hours and talk about the environment.