Cho a, b, c là độ dài 3 cạnh của một tam giác. Chứng minh : `ab + bc + ca ≤ a²+ b²+ c²< 2(ab + bc + ca ).`

III. Choose the best answer 31. We should open all the windows, so we don’t_______use air-conditioners. A. have B. have to C. needn’t D. need 33. Our dream house will use only solar energy so that we can make the______clean and green. A. nature B. environment C. kitchen D. home 35. It takes a lot of energy to keep food cool, so don’t_______the fridge door open or putting hot things inside. A. make B. have C. leave D. stop 36. We have lived in New York __________ a couple of years. A. in B. since. C. for D. at 37. Our houses will use the sun or the wind_______ electricity. A. to have B. to do C. to make D. to give 38. If we all use______bags, we’ll help the environment. A. new B. cheap C. reusable D. reduced 39. Our dream house will be located _______ the ocean. A. on B. at C. in D. between 40. Don’t________old things because perhaps you will need them later. A. throw B. throw away C. throwing D. throwing away 41. Thu __________ the English club twice a week. A. has gone B. went C. goes D. is going 42. It is a good idea to ________our clothes with our friends or cousins. A. change B. swap C. turn D. send 43. I have been _______ many beautiful places in Viet Nam. A. at B. on C. in D. to 44. If there is a rubbish bin in every class, the classroom will become_______. A. harmful B. lighter C. dirtier D. cleaner 45. In the future, robots will be able to do ....................... things than they do now. A. the most complicated B. the more complicated C. more complicated D. most complicated 46. If we use_______paper, we will save a lot of trees. A. fewer B. less C. more D. much 47. Next week our class is having a discussion about finding_______ ways to reuse old items before throwing them away. A. interested B. surprising C. useless D. creative 48. If you have old clothes, will you give them to those_______? A. needs B. to need C. for needing D. in need 49. My brother and I will give last year’s clothes to _______instead of throwing them away. A. shop B. people C. charity D. survey 50. “Robots are helping us a lot in industry, education, and in our house” - “________”. A. I agree with you. B. I hope not. C. Do you agree with that? D. What about you? IV. Find and correct the mistakes. 1. We raise funds by collect waste paper and broken glass. A B C D 2. One of the most popular quiz programme on television is called “Who wants to be a Millionaire”. A B C D 3. Until now, I have visited Da Nang third times. A B C D 4. Because of he was sick all day, he couldn’t finish his assignment. A B C D 5. If we keep on using more and more cars, we are going to run out of oil. A B C D 6. Unless he doesn’t help me, I will finish my homework. A B C D 7. John isn’t in class today. I think he might have sick. A B C D 8. I didn’t have a good seat in the theatre, but I couldn’t see the stage very well. A B C D 9. Did your dad took you to watch the football match last week? A B C D 10. Although the arrival of the storm, they couldn’t finish the football match. A B C D

Vẽ đậu mầm Câu kia chả sai j tự nhiên mod xóa ko thông báo ảo thật đêyyy

Mất gốc tiếng anh thì nên học lại từ đâu và theo lộ trình như thế nào ạ .

MỌI NGƯỜI GIÚP EM VỚI Ạ EM ĐANG GẤP. EM CẢM ƠN Ạ

giải hộ mik bài này với viết ra vở nha

Bài 5 :Cho ∆ABC vuông cân tại A, AM là trung tuyến của ∆ABC. Lấy điểm K thuộc tia đối của tia MA sao cho MK= MA. Kẻ đường thẳng d bất kỳ qua A, Kẻ BH ⊥ d, CE ⊥ d ( H, E ⊥ d ). a)Chứng minh ∆AMB = ∆ KMC và KC // AB. b)Hỏi ∆ AKC là tam giác gì? Vì sao? c)Chứng minh: BH = AE và BH + CE = HE. d)Lấy Q, P lần lượt là trung điểm của AC, CK. Gọi BQ giao AM tại F, AP giao BC tại D. Chứng minh DF  AB. Bài 6 : 1) Cho tam giác ABC cân tại A và góc A = 100 độ . Gọi O là một điểm nằm trên tia phân giác của góc C sao cho góc CBO = 30 độ. Tính góc CAO ? giúp mik làm 2 bài này với mik cảm ơn và sẽ cho 5 sao

Các điều kiện cần có để đảm bảo thành công trong việc truyền đạt thông tin di truyền từ thế hệ tế bào này sang thế hệ tế bào khác ở Eukaryote?

III. Choose the best answer 1. There are two lights _______ the ceiling. A. in B. at C. on D. between 2. Tim hasn’t asked us any questions about the project _____. A. already B. yet C. just D. ever 3. Many plants and animals die because of _______. A. noise pollution B. environment. C. deforestation. D. flood 4. Rising sea level can make some cities _______. A. pollute B. exchange C. appear D. disappear 5. Our class is going to ________ a picnic at the zoo on Saturday. Would you like to come with us? A. have B. take C. pass D. go 6. My best friend is kind and _______. He often makes me laugh. A. nice B. funny C. shy D. boring 7. Listen! Someone _________ at the door. A. knock B. knocks C. is knocking D. are knocking 8. Fred ________ the phone if his wife ________ a bath. A. answer; has. B. will answer; has C. will answer; will have D. answer; will have 9. You should put the food in a reusable box ...................... plastic bag. A. by B. instead of C. because of D. without 10. My neighbourhood is great for outdoor activities______ it has beautiful parks, sandy beaches and fine weather. A. because B. so C. but D. and 11. Ha Noi is _______ exciting than Viet Tri City. A. much B. much more C. more much D. only more 12. The Nile River is the _____ river in the world, _____ the Amazon is the widest. A. long - so B. long - because C. longer - but D. longest - but 13. She arrived ...................... London at five in the afternoon. A. at B. to C. in D. by 14. If you want to go to the Himalayas, you _____ take a waterproof coat because it is cold and rainy there. A. must B. mustn’t C. can D. can’t 15. Plant more trees in the schoolyard because they will provide shade and ______ the atmosphere fresher. A. do B. make C. have D. use 16. ______ the film is late, I will wait to watch it. A. When B. Although C. But D. Because 17. Do you think the _____ time to plant trees is spring? A. good B. better C. best D. well 18. There will be more ……………… problems in the coming years. A. environment B. environmental C. environmentalist D. environmentally 19. Have you ever .................... on a spaceship to the Moon? A. travelled B. travel C. to travel D. travelling 20. We can save a lot of ...................... if we remember to turn off all the electric appliances when we go out. A. electricity B. electrical C. electric D. electrician 21. Is it true that Ha Noi is _______ city in Viet Nam? A. the large B. largest C. larger D. the largest 22. Your vocabulary will get _____ by reading a lot of books. A. nicer B. better C. easier D. higher 23. “______” – “It’s one of the most beautiful beaches in the world”. A. What is My Khe Beach in Da Nang like? B. What does My Khe Beach in Da Nang look like? C. How does My Khe Beach in Da Nang look? D. What does My Khe Beach in Da Nang like? 25. They have waited for John since he ___________ for the school. A. leaves B. has left C. leaving D. left 26. Robots will do most of the housework, _______we will have more time for our family. A. so B. but C. although D. if 27. Unless we_______ cutting trees, we won’t prevent floods and other natural disasters. A. don’t stop B. will stop C. stop D. won’t stop 28. I first ______ to Ha Noi in 2010. A. was B. went C. have been D. have gone 29. All of the machines will have a special card________. A. start B. to start C. starting D. to starting 30. The atmosphere is getting more_______ because there is more smoke from factories and motor engines. A. pollute B. polluting C. polluted D. pollution

Cho tam giác ABC (như hình vẽ ) có MB=Mc, AH=2HM a/tìm các cặp tam giác (Đôi một) có diện tích bằng nhau? Tại Sao? b/Chứng tỏ rằng diện tích 3 tam giác AHB, BHC, CHA bằng nhau.