bài 3 ; một hình trụ có thể tích là 20 bi dm^3 , chiều cao bàng 5 dm . tính diện tích toàn phần của hình trụ đó. bài 4 : cho hcn ABCD có AB =4cm , BC= 5cm /Quay hình chữ nhật đó 1 vòng quanh cạnh AB đc một hình trụ .tính thể tích hình trụ

Các câu hỏi liên quan

1. Can you turn _______________ the light? It’s so dark. (on/off/in/for) 2. What are you looking ______________? My picture book. I’ve lost it. (in/at/ for/off) 3. There are____________ saving methods and inventions to use solar energy. (energetic/energize/energy/energetics) 4. A new air-conditioner will be __________ this morning. (to install/installed/installing/install) 5. I suggest you _______________ to the hospital. (should going/going/should go/to go) 6. He is one of the most famous _______(environment/ environmental/ environmentalists/ environmentalist) 7. Who looks _____________ your children when you are away from home? (after/in/into/for) 8. You must reduce the ____________of water your family uses. (number/amount/many/ much) 9. _________________ is a person who repairs electrical equipment. (plumber/electrician/carpenter/conservationist) 10. It’s raining heavily ________________ I can’t go out. (so/as/but/and) 11. She is worried ____________ her recent water bill. (with/about/as/for) 12. Energy saving bulbs should be used to save ___________ (electric/ electricity/ electrical/ electrician) 13. Solar energy doesn’t cause ______________. (pollution/ polluter/ pollutant/ pollute) 14. A __________ faucet can waste 500 liters of water a month. (dripped/drips/drop/dripping) 15. Ba missed the Math test yesterday. ______________ he will have to do it next week. (Moreover/However/Therefore/And) 16. If _______________were inexpensive and unlimited, many things in the world would be different. (pollution/standard/energy/sewage) 17. A _____________ is a person who installs and repairs water pipes. (plumber/electrician/carpenter/conservationist) 18. A lot of countries in the world are already using ________________ energy. (solar/sun/nuclear/efficiency) 19. Electricity, gas and water are ________________. (luxuries/appliances/necessities/ resources) 20. How about ________________ poster on energy saving and hanging them around our school. (making/make/should make/to make) 21. Remember to turn _____________ the faucet after use. (off/on/up/down) 22. I can’t hear what you’re saying. Can you turn ___________ the radio? (up/down/on/off) 23. Ba is pleased ____________ his English is improving day by day. (that/so/but/therefore) 24. If we go on littering, the environment will become seriously ________ (polluted/ unpolluted/ pollution/polluter) 25. The air in the city is very ____________. (polluted/pollution/ polluter/ pollutant) 26. Turn _____________ the music. It’s too loud. (on/off/in/down) 27. The washing machine was expensive ____________ we couldn’t afford to buy it. (so/but/however/because) 28. He didn’t have much money, ____________ he bought a lot of things at the shop for Tet. (but/or/and/so) 29. The doctor suggested that the secretary _______at least three days off work .(to have/having/should have/has) 30. She suggested __________ for a swim. (going/go/to go/ gone) 31. In winter, heating _________ for 50 percent of our electricity bill. (takes/occupies/accounts/costs) 32. Energy can be collected by solar __________ on cloudy days. (boards/panels/bars/sheets) 33. If we don’t find ______________________ sources of power, we will use up all the fossil fuels in the near future. (effective/efficient/natural/alternative) 34. Are wind power ___________ solar power new kinds of energy for future use? (and/or/with/but) 35. Lan suggested ________to the zoo at weekend. (to go/going/went/to go) 36. Shall we clean up the kitchen, Mum ? ________ (Yes, we do./O.K/No, we don’t./Yes, let’s.) 37. It‘s so hot . Why don’t we go swimming ? ________ (Yes, we do/No, we don’t ./That’s a good idea./Yes, thanks.) 38. Let’s go somewhere for a drink________ (All right./Yes, we do./No, we don’t./No, thanks.) 39. This movie is not interesting . How about ________ to the concert. (to go/going /go/went) 40. You don’t like English food. What about ________Chinese food? (to eat/eat/eating/ate) 41. I think we should ________ up our neighborhood. (to clean/clean/cleaning /cleaned) 42. Our teacher suggests ________a meeting to discuss about the solution to keep our environment clean. (to hold/hold/holding/held) 43. Her former leader suggests that she ________ harder to break her past records. (to train/train/training/trained) 44. The children volunteer to clean up the local park ________ there are lot of used cans and trash there. (but/because/and/so) 45. The “Green Sunday” was short: ________, the students enjoyed it very much. (but/because/however/although)