1.happier

2.more carefully 

3.earlier

4.shorter

6.bigger

7.more special

8.more expensive.

9 .more attractive

10.thinner

11.faster

12.more famous

13.easilier

14.larger

15.more boring

16.more tired 

17.more useful 

18.heavier

19.better

20.more clever

2. Happy → Happier

3. Carefully → More Carefully

4. Early → Earlier 

5. Short → Shorter

6. Big  → Bigger

7. Special → More Special

8. Expensive → More Expensive

9. Attractive → More Attractive

10. Thin → Thinner

11. Fast → Faster

12. Famous → More Famous

13. Easily → Easilier

14. Large → Larger

15. Boring → More Boring

16. Tired → More Tired

17. Useful → More Useful

18. Heavy → Heavier 

19. Good → Better 

20. Clever → Cleverer