...Hùng vĩ của sông Đà không phải chỉ có thác đá. Mà nó còn là những cảnh đá bờ sông, dựng vách thành, mặt sông chỗ ấy chỉ lúc đúng ngọ mới có mặt trời. Có vách đá thành chẹt lòng Sông Đà như một cái yết hầu. Đứng bên bờ này nhẹ tay ném hòn đá qua bên kia vách. Có quãng con nai con hổ đã có lần vọt từ bờ này sang bờ kia. Ngồi trong khoang đò qua quãng ấy, đang mùa hè mà cũng thấy lạnh, cảm thấy mình như đứng ở hè một cái ngõ mà ngóng vọng lên một khung cửa sổ nào trên cái tầng nhà thứ mấy nào vừa tắt phụt đèn điện. Lại như quãng mặt ghềnh Hát Loóng, dài hàng cây số, nước xô đá, đá xô sóng, sóng xô gió, cuồn cuộn luồng gió gùn ghè suốt năm như lúc nào cũng đòi nợ xuýt bất cứ người lái đò Sông Đà nào tóm được qua đấy. Quãng này mà khinh suất tay lái thì cũng dễ lật ngửa bụng con thuyền ra. Lại như quãng Tà Mường Vát dưới Sơn La. Trên sông bỗng có những cái hút nước giống như cái giếng bê tông thả xuống sông để chuẩn bị làm móng cầu. Nước ở đây thở và kêu như cửa cống cái bị sặc. Trên mặt cái hút xoáy tít đáy, cũng đang quay lừ lừ những cánh quạ đàn.... ... Hình như khi mà ta quen đọc bản đồ sông núi , thì mỗi lúc ngồi tàu bay trên chiều cao mà nhìn xuống đất nước Tổ quốc bao la, càng thấy quen thuộc với từng nét sông tãi ra trên đại dương đá lờ lờ bóng mây dưới chân mình. Con Sông Đà tuôn dài tuôn dài như một áng tóc trữ tình, đầu tóc chân tóc ẩn hiện trong mây trờ Tây Bắc bung nở hoa ban hoa gạo tháng hai và cuồn cuộn mù khói Mèo đốt nương xuân. Tôi đã nhìn say sưa làn mây mùa xuân bay trên Sông Đà, tôi đã xuyên qua đám mây mùa thu mà nhìn xuốn dòng nước Sông Đà. Mùa xuân dòng xanh ngọc bích, chứ nước Sông Đà không xanh màu xanh canh hến của Sông Gâm Sông Lô. Mùa thu nước Sông Đà lừ lừ chín đỏ như da mặt một người bầm đi vì rượu bữa, lừ lừ cái màu đỏ giận dữ ở một người bất mãn bực bội gì mỗi độ thu về... Anh chị hãy cảm nhận vẻ đẹp của sông đà qua đoạn trích trên

Tìm m để phương trình x²+mx-3=0 có hai nghiệm phân biệt đều nguyên

Giúp mình giải bài này với mong được kết quả

CMR nếu a,b,c là 3 cạnh của 1 tam giác thì $a^2+b^2+c^2<2(ab+bc+ca)$

D 38. You ___________ do the job if you didn’t speak Japanese fluently. A. couldn’t B. can’t C. won’t be able to D. needn’t 39. When I was young, I __________ go fishing with my father. A. was used to B. would C. may D. used to 40. You ________ take along some cash. The restaurant may not accept credit cards. A. has to B. had better C. can D. could 41. Your wedding ring is very precious. You ___________ lose it. A. must B. could C. needn’t D. mustn’t 42. “How old do you think Peter is?” - “I just looked at his driver’s license. He ______ 33.” A. might be B. may be C. must be D. should be 43. It ________ rain this evening. Why don’t you take an umbrella? A. had better B. might C. must D. could 44. You ________ forget to pay the rent tomorrow. The landlord is very strict about paying on time. A. don’t have to B. mustn’t C. couldn’t D. can’t 45. It’s a school rule. All the students _________ wear a uniform. A. have to B. might C. must D. need 46. Passengers _______ smoke until the signs have been switched off. A. mustn't B. can't C. needn't D. mightn't 47. We must obey the traffic laws. Otherwise, we __________ be punished. A. will B. might C. should D. need 48. This is the key. You _________ forget to take it with you when going out. A. should B. have to C. mustn’t D. needn’t 49. You _________ introduce me to Dr. Gray. We have already met. A. shouldn’t B. needn’t C. mustn’t D. couldn’t 50. “I have got a headache.” – “You _________ go to see the doctor.” A. may B. could C. should D. might

V. Read the following passage and choose the item (a, b, c, or d) that best answers each of the questions about it. My best friend’s full name is Stuart Kenneth Young. His family, call him Ken, for short, but his nickname at school is ‘Sky’! He was born in Manchester, but now he lives in Newcastle. Sky is fifteen years old. He is 1.65m tall and he weighs 50 kilos. He’s got short brown hair and dark brown eyes. He is interested in all kinds of sport and music. His favorite group is U2, but his favorite singer is Bryan Adams. Sports View is his favorite TV program Sky’s favorite food is pizza. He hates people who smoke all the time. I like Sky because he’s got a good sense of humor. I also like him because he’s a great dancer. 27. Who is Stuart Kenneth Young? a. my best friend b. the author’s best friend c. Sky’s classmate d. Sky’s next-door neighbor 28. Where does he live? a. In Newcastle b. In Manchester c. In the United State d. a & b 29. Stuart likes____________ a. all kinds of sport and music b. U2 c. Bryan Adams d. all are correct 30. Stuart is good at________ . a. music b. sport c dancing d. all are correct 31. Which of the following is not true? a. Stuart is fifteen years old. b. Stuart’s eyes are dark brown. c. Stuart likes pizza and people who smoke all the time. d. Stuart has a good sense of humor.

Complete using the correct form of the verb in brackets. 1. Ann .....(watch) TV when the phone rang. 2. A car came around the corner and I .....(jump) out of the way. 3. I chose the hotel because I ....(stay) there before. 4. We ...(wait) for over an hour when the train finally arrived.

27. I often get up early in the morning. A. I’m used to getting up early in the morning B. I’m used to get up early in the morning. C. I used to get up early in the morning D. I used to getting up early in the morning. 28. Please don’t use the shower after midnight A. Would you mind not to use the shower? B. Would you like to use the shower before midnight? C. I don’t want you to use the shower. D. Would you mind not using the shower after midnight? 29. The carpet still needs cleaning. A. The carpet has been cleaned. B. The carpet hasn’t cleaned yet. C. The carpet has not been cleaned. D. The carpet has cleaned. 30. I prefer going out for a meal to staying at home. A. I’d like to go out for a meal. B. Going out for a meal is very interesting. C. I’d rather go out for a meal than stay at home. D. Staying at home is more boring than going out for a meal. 31. He said that he _________ enter the examination room because he was late. A. mustn’t B. couldn’t C. needn’t D. might not 32. “__________ taking me downtown on your way to work this morning?” – Not at all. A. Can you B. Why don’t you C. Could you please D. Would you mind 33. You haven’t eaten anything since yesterday afternoon. You ______ be really hungry! A. must B. might C. will D. can 34. “Why are you so late?” – I _________ take my aunt to the airport. The traffic was terrible!” A. might B. could C. had to D. should 35. I wonder who drank all the milk yesterday. It _____ have been Mary because she was out all day. A. can’t B. must C. could D. needn’t 36. Susan ___________ hear the speaker because the crowd was cheering so loudly. A. might not B. couldn’t C. can’t D. mustn’t 37. Ted’s flight from Britain took more than 11 hours. He _____ be exhausted after such a long flight. A. had better B. can C. must D. should

Cho 0,1 lít dd hỗn hợp gồm H2SO4 0,05 M và HCl 0,1M trung hòa vừa đủ với V lít dd hỗn gồm NaOH 0,2M và Ba(OH)2 0,1M. a) Viết PTHH. b) Tính V (. Có cách nào k dùng định luật bảo toàn nguyen tố không ạ )

17. You shouldn’t tell her the news. It might kill her. A. She shouldn’t be told by the news. She might be killed. B. The news shouldn’t be told her. She might be killed. C. She shouldn’t be told the news. She might be killed. D. She shouldn’t been told the news. It might be killed. 18. It wasn't obligatory to submit my assignment today. A. My assignment must have been submitted today. B. I needn't have submitted my assignment today. C. My assignment was required to submit by today. D. I mustn't submit my assignment today. 19. It's time we left for the disco. A. We may leave for the disco now. B. We needn't leave for the disco now. C. We should leave for the disco now. D. We must have left for the disco now. 20. It was a mistake of you to lose your passport. A. You shouldn't have lost your passport. B. There must be a mistake in your passport. C. You needn't have brought your passport. D. Your passport must be lost. 21. My car keys are possibly in the kitchen. A. My car keys should be put in the kitchen. B. My car keys cannot be in the kitchen. C. I don’t know whether my car keys are in the kitchen. D. My car keys might be in the kitchen. 22. Is it possible for me to come to your house at about 7pm? A. Must I come over to your house at about 7pm? B. Could I be coming to your house at about 7pm? C. Can I come to your house at about 7pm? D. Will I come to your house at about 7pm? 23. You must never take off your helmet while you are riding a motorcycle. A. If you are riding a motorcycle, you needn’t wear a helmet. B. When you are riding a motorcycle, wearing a helmet is not a must. C. You needn’t wear a helmet whenever you are riding a motorcycle D. Helmets must be worn at all times when you are riding a motorcycle 24. I have done this math problem at least twenty times, but my answer is wrong according to the answer key. A. The answer in the book should be wrong! B. The book needn't have a wrong answer. C. There is a wrong answer in the book. D. The answer in the book must be wrong! 25. Can you tell me directions for the station near here? A. Would you tell me where to get to the station near here? B. Could you tell me how to get to the station near here? C. Could you tell me what to get to the station near here? D. Must you tell me the way to get to the station near here? 26. A: John passed his exam with a distinction. B: _______. A. He was too lazy to succeed B. He can't have studied very hard C. He must have studied very hard D. He needs studying harder