Use the right form of the verb (First Conditional):

1. If you (to put) salt on ice, it will melt.
2. If he ( to leave) now, he will miss the rush hour.
3. Provided that she (to service) the car, we’ll be able to drive to the country.
4. Unless he (to do) his homework, he’ll stay at home.
5. They will let us know if they ( to see) him.
6. They all (to be surprised) if I make such a mistake.
7. If he doesn’t come in time, we (to wait) for him?
8. If I (not to be busy), I shall go to the concert.
9. If no one (to come) to help, we shall be obliged to do the work ourselves.
10. If you (to put) on your glasses, you will see better.
11. What shall we do if they (to be late)?
12. Will he be very displeased if I (not to ring) him up?
13. If you (to give) me your address, I shall write you a letter.
14. If my sister doesn’t go to the south, we ( to spend) the summer together.
15. If it (to rain), we shall have to stay at home.