một người đi từ A đến B 1/3 quãng đường AB đi với vận tốc 20km/h, 2/3 thời gian còn lại đi với vận tốc 12km/h, quãng đường cuối đi với vận tốc 15km/h. Tính vận tốc trung bình trên quãng đường AB

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Mn giúp mik với hứa sẽ cho full 50đ nhớ giải thick rõ các bước giải hộ mik nha kết quả thì tui cs r nhưng ko hỉu

45. UNESCO _____ United Nations Educational, Scientific and Cultural Organization. A. stands for B. brings about C. takes after D. gets across 46. Don't forget to ________ your gloves on. It is cold outside. A. let B. make C. put D. fix 47. The passengers had to wait because the plane ______ off one hour late. A. took B. turned C. cut D. made 48. The bomb exploded in the garage; fortunately no one hurt. A. put on B. went off C. got out D. kept up 49. I can’t _____ walking. Can we stop and have a short rest? A. go on B. get on C. go up D. get up 50. You can look __________ these new words in the dictionary if you don't know their meanings. A. up B. after C. for D. out 7. TO- INFINITIVE OR BARE- INFINITIVE I. Choose the best answer to complete each of the sentences/Or identify the underlined part that needs correction: 1. I saw him __________off. A. to drive B. drive C. driven D. drove 2. You’d better ____________ an umbrella. A. take B. to take C. taking D. to be taken 3. Would you mind if I _____________ the window? A. to open B. opened C. opening D. open 4. Wouldn’t you rather _____________? A. succeed B. to succeed C. succeeding D. succeeded 5. He made me __________it all over again. A. done B. do C. to do D. doing

33. The national curriculum is made _______of the following subject: English, Maths, Chemistry and so on... . A. from B. on C. up D. in 34. Shy people often find it difficult to ________ group discussions. A. take place in B. take part in C. get on with D. get in touch with 35. “To give someone a ring” is to __________. A. call him up B. marry him C. admire him D. pick him up 36. Her life was devoted ______ the relief of suffering. A. for B. in C. on D. to 37. Because of heavy rain, the game was ______ for a few days. A. taken out B. put off C. set up D. gotten away 38. What may happen if John will not arrive in time? A. go along B. count on C. keep away D. turn up 39. Johnny sometimes visits his grandparents in the countryside. A. calls on B. keeps off C. takes in D. goes up 40. They decided to postpone their journey till the end of the month because of the epidemic. A. take up B. turn round C. put off D. do with 41. I do not use those things any more. You can _______ them away. A. get B. fall C throw D. make 42. They were late for work because their car _______ down. A. got B. put C. cut D. broke 43. At the station, we often see the sigh “________ for pickpockets”. A. watch on B. watch out C. watch up D. watch at 44. I am late because my alarm clock didn’t _________ this morning. A. come on B. ring out C. go off D. turn on

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úi sời mod vớ vẩn hỏi câu nào sóa câu đấy vẽ đậu mầm vênh mặt

22. How do you start the computer? A. How does the computer turn on? B. How do you turn on the computer? C. How do you turn the computer on? D. Both B and C are correct 23. I/ not accept/ offer/ turn down/ A. I couldn’t accept his offer to avoid turning down him. B. I couldn’t accept his offer because he was turned down. C. I couldn’t accept his offer, so I turned it down. D. I couldn’t accept his offer whether I was turned down. 24. Both Ann and her sister look like her mother. A. take after B. take place C. take away D. take on 25. I’ll be back in a minute, Jane. I just want to try out my new tape recorder. A. resemble B. test C. arrive D. buy 26. They are appealing ____ local business for sponsorship money. A. in B. at C. on D. to 27. The Red Cross is aimed _____ providing medical aid and other help to victims of natural disasters. A. in B. at C. to D. for 28. WHO’s main activities are carrying _____ research on medical development and improving health care. A. out B. in C. for D. of 29. Do you agree that a happy marriage should be based _______ love? A. to B. on C. with D. about 30. The bomb went _________ with a loud bang which could be heard all over the town. A. out B. off C. after D. on 31. Whenever the problems come __________, we discussed them frankly and solved them quickly. A. up B. for C. out D. on 32. Who looks __________ the children when you are going ________ from home? A. out of/ on B. up/ off C. for/ out D. after/ away

1. Cho hàm số y= x^3 - 3x^2 - 3mx + 1. Tìm tất cả giá trị m để hàm số đạt cực trị tại x1, x2 thỏa mãn x1=3.x2 2. Tìm m để hàm số y= -x^3+3x^2+3(m^2-1)x-3m^2x-1 có hai cực trị x1, x2 đồng thời |x1-x2|=2

Làm hộ mk từ câu 11 → câu 22 vs ạ, mk cần gấp