Câu 14: Điền từ thích hợp vào chỗ chấm: a. Ròng rọc..................là ròng rọc chỉ ..............một trục cố định. Dùng ròng rọc ...............để đưa một vật lên cao chỉ có tác dụng thay đổi ............của lực. b. Ròng rọc ...........là ròng rọc mà khi ta kéo dây thì không những ròng rọc quay mà còn...................cùng với vật. Dùng ròng rọc ...............để đưa một vật lên cao, ta được lợi .............về lực.

Các câu hỏi liên quan

III. Complete the sentences using the past simple form of the verbs. 1. I ................at home all weekend.(stay) 2. Angela.................. to the cinema last night . (go) 3. My fiends......................a great time in Nha Trang last year. (have) 4.My vacation in Hue.....................................wonderful (be) 5.Last summer I ...............Ngoc Son Temple in Ha Noi (visit) 6. My parents.................very tired after the trip.( be) 7. I ..........................a lot of gifts for my little sister. (buy) 8.Lan and Mai...............sharks,dolphins and turtles at Tri Nguyen aquarium.(see) 9.Trung........................Chicken and rice for dinner. (eat) 10.They...........about their holiday in Hoi An.(talk) 11. Phuong .............to Ha Noi yesterday (return) 12. We ......................the food was delicious.(think) 13.Yeaterday,I (go) .........................to the restaurant with a client. 14. We ( drive).........................around the parking lot for 20 mins to find a parking space. 15.When we ( arrive).............................at the restaurant , the place ( be)............full 16.The waitress (ask)..........................us if we (have) reservations . 17.I (say), "No, my secretary forgets to make them" 18.The waitress (tell) .......................us to come back in two hours. 19. My client and I slowly ( walk)..........................back to the car. 20.Then we ( see)...................a small grocery store 21. We (stop) in the grocery store and (buy)..................some sandwiches. 22. That (be)..........better than waiting for two hours. 23.I (not go ) ....................to school last Sunday. 24.She (get)......................maried last year? 25.What you ( do)...............last night? - I (do) .................my homework. 26. I (love)...........him but no more. 27. Yesterday, I (get)................up at 6 and (have)......................breakfast at 6.30.