Put the adjectives in the correct form (comparative, superlative) : 1?

Put the adjectives in the correct form (comparative, superlative) : 1. Her dress is (pretty) . Than mine. 2. Cheetahs are (fast) . Animals we can find. 3. Eating fruit and vegetables is (healthy) . Than eating hot dogs. 4. I like milk (good) . Than coffee. 5. China has (many) . People than any other country in the world. 6. The blue whale is (heavy) . Animal in the world. 7. Which is (big) . , Portugal or Spain? 8. Travelling by plane is (comfortable) . Than travelling by car. 9. He is (untidy) . Person in class. 10 Buying things from plastic is (bad) . Than buying things from recycled paper. 11. The Nile is (long) . River in the world. 12. In Mark’s opinion History is (difficult) . Than Geography. However, it is (interesting) . 13. Antarctica is one of (cold) . Places on Earth. 14. Greece is (hot) . Than England. 15. Mirror, mirror on the wall, who’s (pretty) . Of them all? 16. Elvis Presley is one of (popular) . Rock singers ever. 17. Jenny is (tall) . Than Alice even though she is (young) . 18. Switzerland is one of (rich) . Countries in the world. 19. People in Africa are the (poor) . In the world. 20. Alexander the Great was a (good) . Leader than Xerxes.