7. What's the longest river in the world ?
8. the worst
9. the highest/higher
10. the most comfortable

1. is bigger
2. more beautiful
3. most interesting
4. longer
5. most dangerous
6. better
7. more expensive
8. richest
9. worse
10. cleverest
11. more intelligent
12. older
13. larger
14. more boring
15. narrower
16. more busy
17. more quiet
III. Rewrite
1. Your house is smaller than mine
2. The red car is more expensive than the black car
3. That film is more boring than this one
4. Your kitchen is bigger than mine
5. My grandmother is the oldest person in my family
6. Tam is the tallest student in my class
7. My mother can cook better than me
8. Jack can play tennis better than him
9. You spent more money than me
10. This book is not as expensive as it is
11. No one in his class is taller than him 
12. No other films are more interesting than this
13. Japanese cars are the most expensive cars in the world
14. That exercise is not as easy as this one
15. Jack doesn't drive as carefully as he does
16. He can play the best in the group
17. This hotel is the most comfortable in the city
18. The Pacific Ocean is the largest ocean in the world
III. 
1. more interesting
2. fewer
3. larger
4. cleverer/prettier
5. nicer
6. biggest
7. better
8. more powerful
9. richer
10. more difficult