1. If I (have) a tablet PC, I (watch) films on the bus.
2. If he (know) my address, he (visit) me.
3. The air (be) cleaner if people (use) less cars.
4. If you (not go) to bed late, you (not be) tired in the morning.
5. If they (have) clean water to drink, they (not get) so many diseases.
6. If I (be) a teacher, I (not give) so much homework.
7. People (reuse) more plastic bags if they (pay) for them.
8. I (walk) to school if I (live) closer.
9. If the weather (not be) so cold, we (play) outside.
10. If I (see) a ghost, I (run) away.