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copetram_teen
2 năm trước
Để đưa vật có khối lượng 20kg lên cao người ta sử dụng ròng rọc cố định tính lực cần thiết để đưa vật lên đều ( bỏ qua ma sát giữa sợi dây và ròng rọc
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Các câu hỏi liên quan

Câu 1 : Circle the words that are pronounced differently from the rest: 1. A. lead B. great C. seat D. eat 2. A. so B. show C. who D. though 3. A. think B. thank C. that D. three 4. A. door B. zoo C. fool D. soon 5. A. worry B. sorry C. come D. ton 6. A. easy B. dear C. meat D. seat 7. A. bed B. decide C. get D. general 8. A. early B. weather C. heavy D. head 9. A. one B. song C. sorry D. long 10. A. teachers B. thanks C. pupils D. farmers Câu 2 : Select response well correctly first in each of questions following: 1. One of them .................an oval face. A. have B. having C. has D.had. 2. ...........is she? _She is my friend. A. What B. How C. Who D. Whose. 3. I love fruit. I like .............very much. A. carrots B. tomatoes C. peas D.apples. 4. There is .................... bread on the table. A. a B. an C. some D. two. 5. Their cows produce .................. A. a lot of milk B. many milk C. lots milk D. a few milk 6. We are polluting the air .................gases. A. by B. with C. at D. of. 7. What's his job ?- He's a ...............He likes working with children . A. teacher B. engineer C. farmer D. doctor 8. How often do you visit your grandparents ? A. one a week B. once a week C. two week D. twice week 9. Can I help you ? - ......................, thanks. A. No B. Yes C. Sir D. Oh 10. Thanh is going ................. a new bicycle next week. A. to buy B. buying C. to buying D. buy

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