помогите пожалуйста задание 9 и под а и под б

1. The streets in the city are noisier than the streets in the country.

2. The air in the city is dirtier than the air in the street.

3. The buildings in the city are bigger than in the country.

4. Nature in the city is dirtier than nature in the country.

5. Life in the country is quieter than it is in the city.

6. It is dangerous to live in the city than in the country.

7. People in the country are often friendlier than people in the city.