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Exercise 97. Replace the infinitive in brackets by the Present Perfect or Past Indefinite.
1. The children (to do) their homework. Now they can go to the skating-rink. 2. You ever (to be) in Warsaw? — Yes, I (to be) there last year. 3. I already (to send) the telegram. 4. I (to send) the telegram yesterday. 5. I (not to see) him in January. 6. I (not to see) him since January. 7. We (not to receive) any letters from her lately. 8. They (to go) to the camp three days ago. 9. I just (to see) him. 10. I (to see) him in 1998. 11. You (to have breakfast) already? 12. When you (to have breakfast)? 13. When you (to arrive) in Kyiv? 14. He (to fell asleep) at half past seven. 15. I (to known) this engineer since I began to work at the plant. 16. At last I (to written) the composition; now I'll go for a walk.