Put the verbs in brackets into the correct tenses

Put the verbs in brackets into the correct tenses.
1. If I see him, I (give) him a gift.
2. If I had a typewriter, I (type) it myself.
3. If I had known that you were in hospital, I (visit) you.
4. You could make better progress if you (attend) class regularly.
5. If I (know) his telephone number, I'd give it to you.
6. If you (arrive) ten minutes earlier, you would have got a seat.
7. He could get a job easily if he (have) a degree.
8. I shouldn't have believed it if I (not see) it with my own eyes.
9. If she (study) hard, he can pass the exam.
10. If she had asked you, you (accept)?
11. Rice plants (grow) well if there is enough rain.
12. He might get fat if he (stop) smoking.
13. What you (do) if you found a burglar in your house?
14. If she (not hurry), she may be late.
15. If I (try) again, I think that I would have succeed.
16. Water (not run) downhill if there were not gravity.
17. If I tell you a secret, you (promise) not to tell it to anyone else?
18. Tell him to ring me if you (see) him.
19. The police (arrest) him if they catch him.
20. If you (speak) more slowly, he might have understood you.