Put the verbs in brackets into the correct tense (conditional):
1. Plants die if you (not water) them.
2. If I see Tim, I (invite) him to the party.
3. If we all used bicycles, there (not be) so much pollution.
4. If I had known it was your birthday, I (buy) you a present.
1.don't water
2.will invite
3.wouldn't be
4.would buy