4 Key:
1 the smartest; smarter
2 bigger; the most beautiful
3 The best; the most expensive
4 funnier; the funniest
5 closer; longer
6 the most difficult; easier / the easiest
5 Key:
1 Does your pet have feathers?
2 My pet has hairy paws.
3 Guinea pigs live in South America.
4 Do these animals eat leaves?
5 Our country has a lot of high mountains.
6 England is flat.
7 Edinburgh is the capital of my country.
8 The most famous landmark in the area is Big Ben.