Ответ:

I (have been waiting) for a letter from my cousin for a month already, but (have not yet received) it. 13. She has already been doing her homework for two hours; but she has (not yet  done) half of it. 14.1 (have been waiting) for you since two o'clock. 15. What are you ( doing)? — I (am reading). I (have been reading) for two hours already. I have already (read) sixty pages. 16. It is difficult for me to speak about this opera as I (have not  heard) it. 17. I have just  received a letter from my granny, but I have (not yet  received) any letters from my parents. 18. The weather (is) fine today. The sun (has been shining) ever since we got up. 19. Every day I ( wind) up my watch at 10 o'clock in the evening. 20. Come along, Henry, what are you ( doing) now? I (have been waiting) for you a long time. 21. Where are your gloves ? — I (have put) them into my pocket. 22. I (am staying) with some American friends in Chicago. I (have been staying) with them for two weeks now. I ( have had) a great time here. I (have been taking) the opportunity to improve my English. I have already ( seen) the towering skyscrapers of Chicago which are reflected in the rippling water of Lake Michigan. I have just ( taken) a picture of Chicago's Sears Tower which (rises) 1,707 feet and ( provides) a panoramic view from the skydeck. 23. I (am going) to give that cat some food. I (am) sure it (is starving). — But Jane has already ( fed) the cat. You needn't do it.

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