1/ I’ll wait until he (write) __________ his next novel.
2/ When you (come) _______ back, he (already buy) _________
a new house.
3/ Don’t come until I (finish) _________ lunch.
4/ I (hope) ______ it (stop) ____ raining by 5 o’clock this afternoon.
5/ The river (not begin)______ to rise until some rain (fall)______.
6/ I (stay) __________ here until you (finish) _________ your study.
7/ By next month, I (leave) _________ for India.
8/ He (finish) _________ his study before you (leave) __________.
9/ Before you (go) ________, they (leave) _______ the country.
10/ The meeting (finish) ______ by the time we (get) _____ there.
1. the last time played chess was in 2000 - i have not ...
2. i have never met such a famous person before - it is ...
3. my friend's mother has been teaching english in this school for a long time - my friend's mother started .....
4.she has never been so angry before - this is ...
5. the last time it snowed here was six years ago - it hasn't ...
6. he hasn't visited his parents for a year - it's ...
7. john and mary moved to edinburgh twenty years ago- it's now ....
8. john began playing the piano ten years ago - john has ...
9. i have never read such a romantic story - this is ...
10. they last visited me five years ago - they havn't ....
11. he hasn't been back to his homework for 20 years now - it's ...
12. it's nearly twenty years since my father saw his brother - my father ...
13. when did you last ride a bike ? - how long ...
14. we haven't been to london since 1998 - the last ...
15. my wait in the queue has lasted forty minutes so far - i ...
16. i've never seen such a bad film as that one . - that's ....
17. the last time nancy came here was in 1968 - nancy hasn't ...
18. how long have they lived in this city ? - how long ago ...
19. whe did you frist know him ? - how ...
20. philips went on a trip around the world three years ago - it's ..
21. i'm asking you this quesion for the third time - this is ...
22. after that she never got in touch with him - that was the ...
23. we haven't had a party since last christmas - the last time ...
24. she began playing piano six years ago - she has ...
25. when did you last meet him ? how long ...
1. It is years since we last traveled abroad - We haven't ....
2. I haven't watched TV for a week - The last ....
3. We bought this house 2 years ago - we have ....
4. we have never met him before - it's the ....
5. it started to rain at 2p.m - it has ....
6. when did you start working here ? - how long ....
7. dave has written a composition for 2 hours - dave started ....
8. how long have you been learning english ? - when ....
9. keith started driving a car five years ago - keith has ....
10. this is the first time i have ever eaten this kind of food - i have ....
Một máy phát điện xoay chiều cho một hiệu điện thế ở hai cực của máy là 2500V. Muốn tải điện đi xa người ta phải tăng hiệu điện thế lên bằng cách sử dụng một máy biến thế có số vòng dây cuộn sơ cấp là 2500 vòng, cuộn thứ cấp là 20000 vòng.
a) Tính hiệu điện thế hai đầu cuộn thứ cấp.
b) Khoảng cách từ nhà máy điện đến nơi tiêu thụ là 200km, công suất điện cần truyền là 400kW. Tính công suất hao phí do toả nhiệt trên đường dây, biết cứ mỗi km dây dẫn có điện trở 0,1Ω.