10. He runs ( fast ) fastest of all.

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

12. Which planet is (close) closest to the Sun?

13. The weather this summer is even (hot) hotter than last summer.

14. Your accent is ( bad ) worse than mine.

15. Hot dogs are (good) better than hamburgers.

16. They live in a (big) big house, but Fred lives in a (big) biggest one.

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

18. It’s the (large) largest company in the country.