Ответ:
1. He is not working, he is watching the TV programme.
2. Do you know what time we are arriving at the frontier?
3. My elder sister is haveing a music lesson. She always has a music lesson on Friday.
4. Water boils at 100 degrees Centigrade.
5. Why are you walking so fast today? You usually walk quite slowly. - I hurrying. I am afraid to miss the train.
6. Father is reading a newspaper. He usually reads something before going to bed.
7. He is taking his English lesson; he always takes his lessons in the morning.
8. I know that he is leaving for the village tomorrow.
9. What are you reading now? I am reading stories by W. S. Maugham.
10. Mother is cooking breakfast in the kitchen. She always cooks in the morning.
11. Where is John? He is preparing his lessons; he usually prepares it at this time.
12. I can't fetch you because I no longer have my car. I am selling it tomorrow.
13. Why do you speak so fast? You make a lot of mistakes.
14. Who are you waiting for? - I am waiting for Ann, we must leave in ten minutes.
15. I don't understand your remark.
16. The next plane is leaving Salt Lake at six o'clock. You can catch it yet.
17. Go and see what the children are doing.
18. Who are you waiting for? I am wating for my sister.
19. Loren is returning from his honeymoon tomorrow and I'd like to see him before the meeting on Friday.
20. Don't go out, it is raining heavily.
21. You know that we need hundreds of thousands and even millions of skilled workers.
22. Do you understand the use of the Present Indefinite quite well?
23. Cuckoos don't build nests. They use the nests of other birds.
24. Do you usually go through the park? – Not usually, it's only today that I am going here.