11 What ARE you DOING ? — I AM COPYING the text from the text-book now. 12. WILL he GO (IS HE GOING) to Moscow next week?
13. He HASN'T SMOKED (HASN'T BEEN SMOKING) for a month. He is trying to give it up.
14. When did he arrive? - He arrived at 2.00.
15. Had you switched off the light before you left house?
16. I read these books when I was at school. I liked them very much.
17. I couldn't go out because I didn't finish my work.
18. I told you the answer yesterday.
19. What will you do tomorrow in the evening?
20. I didn't meet him last week.
21. I usually leave home at 7 and get here at 12.
22. Here is you watch. I have just found it.
23. Have you had breaskfast yet?
2) The seas_are filled) with poison: industrial and nuclear waste, chemical fertilisers and pesticides.
3) If nothing (is done) about it, one day no animal or plant will be able to live in the seas.
4) Tons of harmful substances(are emitted daily) by industrial enterprises.
5) As globalization continues and the earth’s natural processes transform local problems into international issues, few societiesare left) untouched by major environmental problems.
6) Acid rain, one of the most important environmental problems of all, cannot be seen). The invisible gases that cause acid rain usually come from automobiles or coal-burning power plants.
7) Air pollution can have serious consequences for the health of human beings; the natural ecosystems are affected) severely by it.