. 1. Do machines make labour more productive?
2. Can machines do work in a shorter time?
3. What machines are mounted on a tractor?
4. What self-propelled machines do you know?
5. Are milking machines pow¬ered with electricity?
6. What do modern machines differ in?

1. I have already done my homework. Now I can go for a walk.

2. By this time next week Bill will have passed the exam.

3. I hope it will have stopped snowing before we have to go.

4. I phoned to my friend to find out if he had come home.

5. Autumn has come. It is October now.

6. The film had started when we came to the cinema.

7. The play will not have started before we get to the theatre.

8. She told me she had worked in France before.

9. When I arrived at the airport I realized that I had forgotten my passport.

10. My parents will not have bought a new car by the end of the week.

11. Ben hasn't written the dictation yet.

12. When mother came, my sister already had done her homework.

13. After Jack had found his keys he went for a walk.

14. Have you ever been to Kiev?

15. The Greens will have finished repairing their flat before summer.