1. I ( buy) a book yesterday. 2. I ( buy) a book now. 3. I ( buy) a book tomorrow. 4. I ( buy) a book this week. 5 . I ( buy) books for two hours yesterday. 6. I ( buy)books since last year. 7. What bookyou (buy) last week? 8. What book you ( buy) at this moment? 9. What book -- --you (buy)from 5 to 6 yesterday? 10. What books (ты собираешься купить)?

1) Sam repaired his can yesterday. Sam did not repair his can yesterday. Did Sam repair his can yesterday?
2) Alice is jumping on her bed now. Alice is not jumping on her bed now. Is Alice jumping on her bed now?
3) My parents will fly to America next week. My parents will not fly to America next week. Will my parents fly to America next week?
4) Anna waters the flowers every day. Anna doesn’t water the flowers every day. Does Anna water the flowers every day?
5) You have already made the bed. You haven’t made the bed yet. Have you already made the bed?

The scientists have already written their 3article.
1. Pete’s hamster has just eaten his food.
2. The boys found yesterday an old cage in their garden.
3. He hasn't discussed the problem yet
4. Charles has jusr finished his dictation.
5. We went to the theatre last Sunday.
6. Kate has been to the library three times this week.
7. Don’t buy pizza! I  have already cooked an apple pie.
8. Let’s have breakfast! Mike has just set the table.
10.My mother is angry. My elder sister hasn't taken out rubbish.

9. I know who your boss is. I have worked for him.
10. Look! Somebody has already broken the tree.
11. Mary has gone to Moskow, but she’ll be back next Monday at the latest.
12. Andy is in hospital now. He has had a bad crash.
13. Jane is crying. She has hurt her knee.