Sure! Here are the answers to the questions based on the text:

**21.** What is the main idea of the passage?
- **B. The effects of pollution on the environment.**

**22.** The role of education in environmental protection is:
- **C. preserve.**

**23.** The word “they” in the fourth paragraph refers to:
- **C. people.**

**24.** Which of the following is NOT mentioned in the passage?
- **D. The role of laws in combating climate change.**

**27.** "Do many people speak English in India?" he asked.
- **A. He asked me do many people speak English in India.**

**28.** I prefer watching English movies to reading English novels.
- **B. I prefer watching English movies than reading English novels.**

**29.** Join an English club and you will meet new friends.
- **A. You will make friends if you join an English club.**

**30.** If you think that they can’t speak English fluently.
- **A. They can’t speak English fluently.**

**31.** I found vocabulary easier than grammar.
- **A. Learning grammar was harder than vocabulary for us.**

If you have more questions or need further assistance, feel free to ask!