Đáp án:

1. Huong has a new school bag

2. Are there forty classrooms in Phong's school ?

3. This house is the oldest house on the street

- older → oldest

4. How about listening to music tonight

- How about + N/V-ing?

5. What is the price of this dictionary?

1. Huong's school bag is new.

Huong has a new school bag.

2. Does Phong's school have forty classrooms?

Are there forty classrooms in Phong's school? 

3. No houses on the street are older than this house

This house is the oldest house on the street.

4. Why don't we listen to music tonight

How about listening to music tonight?

5. How much is this dictionary?

What is the price of this dictionary?