2.Air/countryside/heathy/city

=>The air in the countryside is healthier than The air in the city

3.People/countryside/work/hard/city

=>People in the countryside work harder than People in the city

4.This paddy field/large/five stadiums

=>This paddy field is larger than five stadiums

5.A cow/plough/bad/a buffalo

=>A cow ploughs worse than a buffalo

6.Mai/speak English/fluent/her sister

=>Mai speaks E more fluently than her sister does

7.Summer/hot/autumn

=>Summer is hotter than autumn

8.Life/countryside/peaceful/city

=>Life in the countryside is more peaceful than life in the city

9.An ox/strong/a horse

=>An ox is stronger than a horse

10.Quang/write/careful/his friends

=>Quang writes more carefully than his friends do