Ex.1
1. fattest
2. heavier
3. tallest
4. most attractive
5. colder
6. most beautiful
7. better; better; best
8. lighter
9. a warmer
10. faster
11. tallest
12. quiet; quieter
13. delicious

Ex.2
1. The Mona Lisa is the most famous painting in the world = "Мона Лиза" - самая известная картина мира.
2. The Volga is longer than the Don (наверное, я не знаю) = Волга длиннее Дона.
3. Germany is more beautiful than Spain (на моё усмотрение) = Германия красивее Испании.
4. London is the biggest city in England = Лондон - самый большой город Англии.
5. Adam is the worst player in the team = Адам - худший игрок в команде.

Ex.3
1. He is the oldest student in the group.
2. You are taller than me.
3. My car is better than his.
4. It's one of the most beautiful lake in the world.
5. These flowers are cheaper than those.

Ex.4
1. An is sadder now than she was in the morning.
2. The 5th of May was the worst day of his life.
3. He is the happiest man in the world.
4. My brother's room is bigger than his.
5. Your son is the politest boy in the class.
6. He took his heavy bag.
7. Peter is my best friend.
8. James's grandmother is older than his grandfather.
9. Your chair is more comfortable than my stool.
10. He is the most famous architect in our city.