B

1. Your brother is more optimistic than you.
2. The air in the countryside is healthier than in the city.
3. People in the countryside work harder than in the city.
4. This paddy field is larger than five stadiums.
5. A cow ploughs worse than a buffalo.
6. Mai speaks English more fluently than her sister.
7. Summer is hotter than autumn.
8. Life in the countryside is more peaceful than in the city.
9. An ox is stronger than a horse.
10. Quang writes more carefully than his friends.