Change the adjectives to their comparative forms. Chuyển các tính từ sang dạng so sánh hơn 1. crowded more crowded11. dirty _____________2. funny _____________12. bad _____________3. boring _____________13. thin _____________4. good _____________14. thoughtful _____________5. attractive _____________15. noisy _____________6. hard _____________16. generous _____________7. difficult17. wise _____________8. eniovable _____________18. polluted _____________9. friendlv _____________19. busy _____________10. common _____________20. narrow _____________Hướng dẫn giải 1. more crowded 2. funnier 3. more boring 4. better 5. more attractive 6. harder 7. more difficult 8. more eniovable 9. more friendly 10. more common 11. dirtier 12. worse 13. thinner 14. more thoughtful 15. noisier 16. more generous 17. wiser 18. more polluted 19. busier 20. more narrow