1. Look at these children: they are skating very well. 2. Did you skate last Sunday? — Yes, we were skating the whole day last Sunday. We shall skate again next Sunday. 3. My brother can skate very well. He skates every Sunday. 4. What are you doing now? — I am washing the dishes. 5. What were you doing at three o'clock yesterday? — I was having dinner. 6. Are you having dinner now? 7. Where does your brother work? — He works at an institute. 8. Were your grandmother sleeping when you came home yesterday? 9. What will your brother do tomorrow? 10. I didn't go to the shop yesterday. I'll go to the shop tomorrow. 11. Where was Kate going when you met her yesterday? 12. Every day the boss enters the office at nine o'clock. 13. Yesterday the boss entered the office at half past nine. 14. When will the secretary come tomorrow? 15. At six o'clock yesterday we were listening to a very interesting lecture. 16. When I entered the office, the secretary was typing some letters. 17. My friend rang me up at eight o'clock yesterday.