Dưới đây là các câu hoàn thành:

1. The black car is cheaper than the red car.
**The red car is more expensive than the black car.**

2. It is good if we can use less plastic bags.
**We should use fewer plastic bags.**

3. It is good to finish your homework after school.
**You should always do your homework promptly.**

4. It is not good for anyone to break things on the first day of New Year.
**Anyone should not break things on that day.**