Cần gấp XĐBT 1. √ 5 − 2 x 2. √ x − 1 x + 1 /x − 3 4.căn x^2-6x+7 5.căn x^2+7

Hoà tan 2,8g sắt bằng dung dịch hcl 2M a) tính thể tích dung dịch hcl cần dùng b) tính thể tích khí hidro thoát ra ở điều kiện tiêu chuẩn Giúp mình với

A. Choose the best answer among A, B, C or D to complete each sentence. 1.He was writing to his friend when he __________a noise. A. was hearing B. heard C. had heard D. hears 2. I __________many people since I came here in June. A. met B. has met C. was meeting D. have met 3. We __________ maths at this time last week. A. were learning B. are learning C. was learning D. learnt 4. She was playing games while he __________a football match. A. watched B. watches C. was watching D. watching 5. She __________to Ho Chi Minh city last year. A. goes B. has gone C. go D. went 6. Since we came here, we ______ a lot of acquaintances. A. have had B. had C. have D. are having 7. __________he playing football now? A. Will B. Does C. Was D. Is 8. Every morning, I often sit in my garden and____ to my nightingale sing. A. listening B. listen C. listened D. listens 9. She __________school when she was six. A. start B. started C. has started D. are starting 10. I. __________TV when the telephone rang. A. watched B. was watching C. are watching D. have watched 11. She__________ lunch by the time we arrived. A. had finished B. finished C. have finished D. finishing 12. This record-shop__________ be a book-shop a few years ago. A. used to B. use C. used D. used 13. I couldn’t come to the party because I __________go to work. A. have B. had to C. have got D. had 14. Yesterday, I _______ for work late because I _______ to set my alarm. A. had left / forgot B. was leaving / was forgetting C. left / had forgot D. had been leaving / would forget 15. By the time we ____ to the train station, Susan _____ for us for more than two hours. A. will get / has been waiting B. got / was waiting C. got / had been waiting D. get / will wait 16. While her brother was in the army, Sarah ___________ to him twice a week. A. was writing B. wrote C. has written D. had written 17. The Titanic _______ the Atlantic when it _______ an iceberg. A. was crossing / struck B. had crossed / was striking C. crossed / had struck D. is crossing / strikes 18. In the 19th century, it _______ two or three months to cross North America by covered wagon. A. took B. had taken C. had taken D. was taking 19. Last night at this time, they _______ the same thing. She ______ and he ­­­­­­­­­­­­­­­­_________ the Newspaper. A. are not doing / is cooking / is reading B. were not doing / was cooking / was reading C. was not doing / has cooked / is reading D. had not done / was cooking /read 20. When I _____ home last night, I ____that Jane ______ a beautiful candlelight dinner. A. had arrived / discovered / prepared B. was arriving / had discovered / was preparing C. have arrived / was discovering / had prepared D. arrived / discovered / was preparing 21. After he ____________ his English course, he went to England to continue his study. A. finish B. finishes C. finished D. had finished 22. Angelina Jolie is a famous actress. She ________ in several films. A. appears B. is appearing C. appeared D. has appeared 23. Mai____ in HCM for five years. A. lives B. has lived C. is living D. was living 24. My little sister________ “sleeping beauty” several times. A. watches B. is watching C. has watched D. watched 25. I ______ to New York three times this year. A. have been B. was C. were D. had been 26. I ______ her since I _____ a student. A. know/ am B. knew/ was C. have known/ am D. have known/ was 27. The train _____ when we got to the station. A. just left B. just leaves C. had just left D. will leave 28. Her father ______ when she was a small girl. A. dies B. died C. has died D. had died 29. Almost everyone _______ for home by the time we arrived. A. leave B. left C. leaves D. had left 30. I ______ to the same barber since last year. A. am going B. have been going C. go D. had gone

31. He ………….. in the same house since 1975. A. has lived B. is living C. lived D. had lived 32. When I came to visit her last night, she ________ a bath. A. is having B. was having C. has D. had 33.When we arrived at the restaurant, the others __________ . A. left B. have left C. had left D. are leaving 34. By the end of 2010 we_______ in Ho Chi Minh City for 30 years. A. work B. will work C. have worked D. will have worked 35. I learned that the college ________ in 1900 A. found B. was founded C. founded D. had been founded 36. If I ________ 10 years younger, I _________ the job. A. am/ will take B. were/ would take C. would be/ took D. had been / would take 37. By the time he _____________ to the meeting, it had begun for 15 minutes. A. had gone B. has gone C. went D. was going 38. He began to feel ill while ___________________. A. he is doing the exam B. he did the exam C. he would do the exam D. he was doing the exam. 39. Since 1980, scientists the world over _____ a lot of things to fight against AIDS. A. have done B. are doing C. did D. had done 40. Now my sister _____ a bicycle of her own. A. is having B. are having C. has D. had 41. Last week, my professor promised that he _____ A. would come B. will come C. comes D. coming 42. My girl friend arrived after I _____ for her about half an hour. A. was waiting B. had been waiting C. have been waiting D. have waited 43. I _____ in Quang Ngai before I moved to Binh Thuan. A. have been living B. have lived C. had lived D. had been living 44. There are many ways _____ to Rome. A. is leading B. are leading C. leading D. led 45. While I ____________ T.V last night, a mouse ran across the floor. A. watch B. watched C. am watching D. was watching 46. I still can’t believe it! My bicycle _________ last night. A. was stolen B. had been stolen C. stole D. was being stolen 47. While they were ________tables, he was _________ the radio. A. arranging – listening to B. arranging – hearing C. laying -listening to D. making- hearing 48. I suddenly remembered that I ……..to bring my keys. A. having forgotten B. have forgotten C. had forgotten D. forgot 49. By the year 2010 many people currently employed ________their jobs. A. will have lost B. will be losing C. have lost D. are losing 50. By September next year I_______ here for ten years. A. will be working B. work C. will have been working D. have been working

11. She…………….Hanoi last year A. went B. go C. goes D. is going 12. Now you ………………from New York to Los Angeles in a matter of hours A. are flying B. would fly C. will fly D. can fly 13. When Carol………………..last night, I…………….my favorite show on television A. was calling- watched B. called- have watched C. called- was watching D. had called- watched 14. By the time next summer, you………………..your studies A. completes B. will complete C. are completing D. will have completed 15. Right now, Jim……………..the newspaper and Kathy……………dinner A. reads- has cooked B. is reading- is cooking C. has read- was cooking D. read- will be cooking 16. Last night at this time, they…………………………..the same thing. She……………..and he…………the newspaper A. are doing- is cooking- is reading B. were doing- was cooking- was reading C. was doing- has cooked- is reading D. had done- was cooking- read 17. Sam…………..to change a light bulb when he…………….and……………………. A. was trying-slipped- fell B. tried- was slipping- falling C. had been trying- slipped- was falling D. has tried- slips- falls 18. Every day I ______up at 6 o’clock, ____breakfast at seven o’clock and_____for work at 8 o’clock A. get- eat- leave B. have got- eating- leaving C. got- ate- left D. will get- have eaten- left 19. I_____ for this company for more then thirty years, and I intend to stay here until I_____next year A. am working- will retire B. am going to work- am retiring C. work- am going to retire D. have been working- retire 20. My mother is the first……………..up and the last………………….to bed A. getting- going B. to get- going C. getting- to go D. to get- to go 21. I must have a bath. I ………………….all the afternoon A. was gardening B. have gardened C. have been gardening D. had been gardening 22. The team……………..a single match so far this season A. doesn’t win B. didn’t win C. hasn’t won D. hadn’t won 23. By the time you receive this letter, I …………….for the USA A. have left B. will leave C. will have left D. am leaving 24. Up to now, the manager ………………..a lot of information about his secretary. A. learned B. has learned C. had learned D. learns 25. Where is Mary? _ She ……………her homework in her room. A. is performing B. is making C. is doing D. is learning 26. While I ……………….along the road, I saw a friend of mine. A. was cycling B. have cycled C. cycled D. am cycling 27. By the time I . . . . . . . . . . this report, I will give you a ring. A. type B. will type C. have typed D. will have typed 28. While my mother ________ a film on TV, my father was cooking dinner. It was March 8th yesterday. A. watched B. was watching C. had watched D. watches 29. The plane from Dallas ________ two hours late, so I missed my connecting flight from Frankfurt to London. A. took on B. took in C. took over D. took off 30. When we came, a party _________ in the hall. A. is being held B. had being held C. will be held D. was being held

hãy nêu cảm nhận của em về hình ảnh người lớn trong buổi tựu trường đầu tiên của trẻ em ở văn bản '' tôi đi học '' ?

Giúp mik vs đc ko ạ mik đag cần gấp ạ

Giúp em bài này với ạ em cảm ơn

Để đánh giá trữ lượng cá trong hồ người ta đánh bắt 2000 con cá đánh dấu rồi thả xuống hồ. Sau đó bắt lại 400 con thì thấy 80 con có dấu. Với độ tin cậy 95%, hãy ước lượng trữ lượng cá trong hồ.

Mn làm giúp em bài này với em cảm ơn nhiều