1. the most beautiful 
2. the most interesting
3.  the most amazing 
4. the most difficult mountain
5. the most boring

6. the most delicious
7. the most polluted
8. the most valuable

VII.
1.warmer
2. the most beautiful
3. more difficult
4. the oldest
5. the most populated
6. worse
7. the best
8. more crowded
9. largest 
10. the most modern
VIII.
1. more crowded than
2. the most romantic
3. more expensive than
4. the most famous
5. the biggest
6. more interesting than
7. hotter than
8. the most beautiful
IX.
1. have had
2. has taught 
3. haven't stopped
 4. have found
5. hasn't seen
6. has broken
7. haven't decided
8. have already finished
9. hasn't played
10. have been
X.
1. were
2. have been
3. will cycle
4. am staying
5. didn't do
6. has taught
7. went - had 
8. arrives
XI.
1. What continent is Brazil in?
2. What is the capital city of Australia?
3. What has the weather in Stockholm been?
4. How big is New York?
5. How long have you lived in New York?
6. When did your family move to Sydney?
7. Where have you never been to?
8. How did he travel to Mexico?
XII.
1. haven't had
2. haven't had
3. has gone
4. moved
5. Have- visited
6. has lived
7. Did - go
8. have worked
9. Have -seen
10. broke
XIII.
2. What awful weather!
3. What a beautiful city!
4. What attractive buildings!
5. What a delicious cake!
6.  What lovely flowers!
7. What strong coffee!
8. What an interesting Maths lesson!
mình xin hay nhất ạ :)