1. He is the cleverest student in my group.

2. She can't stay longer than 30 minutes.

3. It's the best holiday I' ve had.

4. Well, the place looks cleaner now.

5. The red shirt is better but it's more expensive than being a builder.

6. l'll try to finish the job more quickly than the white one.

7. Being a firefighter is more dangerous than being a builder.

8. Lan sings more sweetly than Hoa.

9. This is the most exciting film I've ever seen.

10. He runs the fastest of all.

11. My Tam is one of the most popular singers in my country.

12. Which planet is  the closest to the Sun?

13. Carol sings as beautifully as Mary,but Cindy sings the most beautifully

14. The weather this summer is even hotter than last summer.

15. Your accent is worse than mine.

16. Hot dogs are better than hamburgers.

17. They live in a big house,but Fred lives in a bigger one.

18. French is considered to be more difficult than English, but Chinese is the the most difficult language.

19. It's the largest company in the country.

20. I think that maths is more difficult than English

C1. the cleverest

C2. longer

C3. the best

C4. cleaner 

C5. more expensive

C6. more quickly

C7. more dangerous

C8. more sweetly

C9. he most exciting

C10. the fastest

C11. the most popular

C12. the closest

C13. beautifully/ the most beautifullly

C14. hotter 

C15. worse 

C16. better

C17. big/ bigger 

C18. more difficult / the most difficult 

C19. largest

C20. more difficult

Chúc bạn học tốt !!🙆

@Katniss