1. This car is more expensive than that car.

2. The air in the city is often more polluted than in the countryside.

3. Nobody in Giang's class is better at English than Giang. 

$S_1$ + be + short adj + er/more + long adj + than + $S_2$.

→$S_2$ + be + short adj + er/more + long adj (tính từ trái ngược) + than + $S_1$.

4. How often do you go to the English club?

How many times do/does S + V?

→How often do/does + S + V?

5. My brother usually walks to school.

S + go on foot.

→S + walk.