Упр. 172. Раскройте скобки, употребляя глаголы в Present Simple либо Future

Упр. 172. Раскройте скобки, употребляя глаголы в Present Simple либо Future Simple. (Все предложения относятся к будущему).
1. When he (to return) to St. Petersburg, he (to call) on us. 2. If I (to see) him, I (to tell) him about their letter. 3. We (to gather) at our place when my brother (to come) back from Africa. 4. I (to sing) this song with you if you (to tell) me the words. 5. I hope you (to join) us when we (to gather) in our country house the next time. 6. What you (to do) when you (to come) home? 7. If I (to stay) some more days in your town, I (to call) on you and we (to have) a good talk. 8. He (to go) to the Public Library very often when he (to be) a student. 9. As soon as I (to return) from school, I (to ring) you up. 10. You (to pass) many towns and villages on your way before you (to arrive) in Moscow. 11.1 (to stay) at home till she (to come). Then we (to go) to the theatre if she (to bring) tickets. 12. After I (to finish) school, I (to enter) the University.