b. Fill in the blanks. (Điền vào chỗ trống.)
1. The air will be (be) less polluted if we use (use) school buses or public transportation.
2. If students __________ (not stop) littering, our school __________ (be) full of trash.
3. Students __________ (not litter) if we __________ (make) them clean the school.
4. Our school __________ (be) cleaner if we __________ (ban) single-use plastic.
5. If we __________ (reuse) water bottles, there __________ (be) less trash.
6. If there __________ (be) more recycling bins, it __________ (be) easier to recycle.