MỤC LỤC CHUYÊN ĐỀ 1: NGỮ ÂM ............................................................................................................................................................. 0 CHUYÊN ĐỀ 2: CÁC THÌ ............................................................................................................................................................... 5 CHUYÊN ĐỀ 3: BỊ ĐỘNG ............................................................................................................................................................. 9 CHUYÊN ĐỀ 4: CÂU ĐIỀU KIỆN ................................................................................................................................................. 13 CHUYÊN ĐỀ 5: CÂU GIÁN TIẾP ................................................................................................................................................. 17 CHUYÊN ĐỀ 6: MỆNH ĐỀ QUAN HỆ.......................................................................................................................................... 21 CHUYÊN ĐỀ 7: MỆNH ĐỀ CHỈ NGUYÊN NHÂN.......................................................................................................................... 25 CHUYÊN ĐỀ 8: MỆNH ĐỀ CHỈ KẾT QUẢ .................................................................................................................................... 27 CHUYÊN ĐỀ 9: MỆNH ĐỀ CHỈ TƯƠNG PHẢN ........................................................................................................................... 31 CHUYÊN ĐỀ 10: MỆNH ĐỀ CHỈ MỤC ĐÍCH ............................................................................................................................... 35 CHUYÊN ĐỀ 11: ĐỘNG TỪ KHUYẾT THIẾU ............................................................................................................................... 39 CHUYÊN ĐỀ 12: GIỚI TỪ + MẠO TỪ ......................................................................................................................................... 43 CHUYÊN ĐỀ 13: TỪ LOẠI .......................................................................................................................................................... 47 CHUYÊN ĐỀ 14: DẠNG ĐỘNG TỪ ............................................................................................................................................. 51 CHUYÊN ĐỀ 15: TÌM VÀ SỬA LỖI SAI ........................................................................................................................................ 55 CHUYÊN ĐỀ 16: TỪ VỰNG ........................................................................................................................................................ 59 CHUYÊN ĐỀ 1: NGỮ ÂM I. Different sound 1. A. heat B. scream C. meat D. dead 2. A. prepared B. particular C. pagoda D. attract 3. A. thrilling B. other C. through D. something 4. A. idea B. going C. will D. trip 5. A. face B. place C. prepared D. days 6. A. around B. sound C. only D. mouse 7. A. teacher B. other C. together D. term 8. A. Germany B. garden C. gate D. gas 9. A. scholarship B. Christ C. school D. chicken 10. A. house B. harm C. hour D. husband 11. A. sing B. morning C. any D. hang 12. A. hundred B. exhausted C. however D. heat 13. A. head B. ready C. mean D. weather 14. A. choir B. cheap C. child D. chair 15. A. charge B. child C. teacher D. champagne 16. A. reason B. clear C. mean D. each 17. A. motion B. question C. mention D. fiction 18. A. gather B. good C. large D. again 19. A. change B. children C. machine D. church 20. A. hand B. bank C. sand D. band 21. A. cooks B. loves C. joins D. spends 22. A. share B. rare C. are D. declare 23. A. clothes B. cloths C. roofs D. books 24. A. naked B. looked C. booked D. hooked 25. A. laughed B. weighed C. helped D. missed 26. A. apply B. university C. identity D. early 27. A. choice B. achieve C. each D. chemistry 28. A. final B. applicant C. high D. decide 29. A. average B. indicate C. application D. grade 30. A. course B. four C. our D. yours 31. A. worker B. whom C. interview D. answer 32. A. honest B. holiday C. home D. happiness 33. A. character B. teacher C. chemist D. technical 34. A. interview B. minute C. question D. suitable 35 A. explained B. disappointed C. prepared D. interviewed 36. A. economy B. industry C. qualify D. priority 37. A. right B. private C. communist D. minority 38. A. measure B. subsidies C. domestic D. hospital 39. A. though B. encourage C. enough D. country 40. A. improve B. introduce C. move D. lose 41. A. future B. mature C. pasture D. nature 42. A. chore B. technology C. much D. exchange 43. A. threaten B. earth C. healthy D. breathe 44. A. wipe B. allow C. powerful D. answer 45. A. service B. practice C. office D. device 46. A. grasses B. stretches C. comprises D. potatoes 47. A. lie B. wide C. circle D. comprise 48. A. compound B. route C. house D. south 49. A. dune B. hummock C. shrub D. buffalo 50. A. west B. between C. growth D. which II. Stress 1. A. comprise B. sandy C. circle D. northern 2. A. Aborigines B. expedition C. kilometer D. scientific 3. A. corridor B. enormous C. mystery D. separate 4. A. remain B. hummock C. explore D. between 5. A. territory B. Australia C. geography D. society 6. A. eject B. crossbar C. except D. commit 7. A. canoeing B. opponent C. windsurfing D. defensive 8 A. participant B. publicity C. competitive D. individual 9 A. interfere B. memory C. personal D. vertical 10 A. award B. defeat C. refer D. scuba 11.A. social B. conduct C. survey D. value 12.A. marvelous B. attention C. consider D. excited 13.A. verbal B. whistle C. precede D. marriage 14.A. attract B. decide C. reject D. beauty 15.A. solution B. suitable C. confidence D. family 16. A. conical B. determine C. contractual D. supportive 17. A. physical B. mischievous C. suitable D. romantic 18. A. ancestor B. measurement C. counterpart D. appearance 19. A. commitment B. inflation C. collection D. enterprise 20. A. dissolve B. observe C. publish D. appraise 21. A. technology B. psychology C. reconstruction D. apology 22. A. between B. result C. ago D. coffee 23. A. waving B. teaching C. pointing D. divide 24. A. student B. listen C. blackboard D. between 25. A. traditional B. professional C impossible D. decoration 26. A. economics B. interfere C. philosophy D. punctuality 27. A. secondary B. primary C. fantastic D. national 28. A. education B. curriculum C. technology D. integrity 29. A. because B. method C. standard D. wooden 30. A. ashtray B. music C. severe D. temper 31. A. farewell B. thoughtful C. toward D. approach 32. A. mischievous B. family C. supportive D. suitable 33. A. desert B. parallel C. hummock D. aerial 34. A. measure B. pressure C. unwise D. sacrifice 35. A. attitude B. partnership C. actually D. Vietnamese 36. A. survey B. enormous C. remained D. mystery 37. A. diversity B. marriage C. engagement D. importance 38. A. European B. Victorian C. Brazilian D. Korean 39. A. America B. equal C. maintain D. attractive 40. A. confide B. reject C. precede D. conical 41. A. expedition B. exploration C. Australian D. Geographical 42. A. appropriate B. interesting C. different D. cultural 43. A. culture B. engage C. majority D. determine 44. A. romantic B. counterpart C. discussion D. appearance 45. A. bridegroom B. bamboo C. wedding D. survey 46. A. supernatural B. explanation C. redundancy D. electronic 47. A. gymnastics B. criminal C. investment D. excitement 48. A. financial B. ambitious C. refusal D. evidence 49. A. confess B. function C. jealous D. patient 50. A. possibility B. manufacture C. instrument D. disappointed CHUYÊN ĐỀ 2: CÁC THÌ 1. When I got home I found that water...............................down the kitchen walls A. ran B. was running C. has run D. had been running 2. After he.......................his English course, he went to England to continue his study A. has finish B. had finished C. was finished D. would finish 3. How.........................since we .....................college? A. are you- left B. were you- left C. have you been- have left D. have you been- left 4. I..................much of you lately. We..........................three months ago A. haven’t seen- last meet B. didn’t see- met C. haven’t seen- have meet D. didn’t see- have met 5. The Chinese.......................spaghetti dishes for a long time before Marco Polo.................back to Italy A. made- brought B. have made- brought C. made- had brought D. had been making- brought 6. When I arrived at the meeting the first speaker.................speaking and the audience................... A. just finished- were clapping B. had just finished- had clapped C. had just finished- were clapping D. just finished- had clapped 7. He.............................his job last month and then he..................out of work A. lost- was B. was lost- had been C. has lost- was D. lost- has been 8. In the last hundred years, travelling.......................much easier and more comfortable A. become B. has become C. became D. will became 9. In the 19th century, it.............two or three months to across North America by covered wagon A. took B. had taken C. had been taken D. was taking 10. In the past, the trip...................very rough and often dangerous, but things..........a great deal in the last hundred and fifty years A. was- have changed B. is- change C. had been- will change D. has been- changed 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 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 _____ today. 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 CHUYÊN ĐỀ 3: BỊ ĐỘNG 1. We can’t go along here because the road........................ A. is repairing B. is repaired C. is being repaired D. repairs 2. The story which I’ve just read...................Agatha Christie A. was written B. was written by C. was written from D. wrote by 3. I’m going to go out and................................................. A. have cut my hair B. have my hair cut C. cut my hair D. my hair be cut 4. Something funny ...........................in class yesterday A. happened B. was happened C. happens D. is happened 5. Many US automobiles........................in Detroit, Michigan A. manufacture B. have manufactured C. are manufactured D. are manufacturing 6. A lot of pesticide residue can.........................................unwashed produce A. find B. found C. be finding D. be found 7. We..................by a loud noise during the night A. woke up B. are woken up C. were woken up D. were waking up 8. Some film stars...................difficult to work with A. are said be B. are said to be C. say to be D. said to be 9. Why did Tom keep making jokes about me? – I don’t enjoy........................at A. be laughed B. to be laughed C. laughing D. being laughed 10. Today, many serious childhood diseases...........................by early immunization A. are preventing B. can prevent C. prevent D. can be prevented 11. Do you get your heating..........................every year? A. checking B. check C. be checked D. checked 12. Bicycles.......................in the driveway A. must not leave B. must not be leaving C. must not be left D. must not have left 13. Beethoven’s Fifth Symphony.......................next weekend A. is going to be performed B. has been performed D. will be performing D. will have perform 14. All bottles......................................before transportation A. frozen B. were froze C. were frozen D. are froze 15. ...............................................yet? A. Have the letters been typed B. Have been the letters typed C. Have the letters typed D. Had the letters typed 16. English has become a second language in countries like India, Nigeria or Singapore where.................for administration, broadcasting and education A. is used B. it is used C. used D. being used 17. The telephones..............by Alexander Graham Bell A. is invented B. is inventing C. invented D. was invented 18. Lots of houses...................by the earthquake A. are destroying B. destroyed C. were destroyed D. is destroyed 19. Gold.........................in California in the 19th century A. was discovered B. has been discovered C. was discover D. they discover 20. The preparation.......................by the time the guest............................ A. had been finished- arrived B. have finished- arrived C. had finished-were arriving D. have been finished- were arrived 21 The boy_____ by the teacher yesterday. A. punish B. punished C. punishing D. was punished 22. “Ms Jones, please type those letters before noon”_ “They’ve already ______, sir. They’re on your desk.” A. typed B. been being typed C. being typed D. been typed 23. Sarah is wearing a blouse. It___________ of cotton. A. be made B. are made C. is made D. made 24. They had a boy _______ that yesterday. A. done B. to do C. did D. do 25. We got our mail ______ yesterday. A. been delivered B. delivered C. delivering D. to deliver 26. James..the news as soon as possible. A. should tell B. should be told C. should told D. should be telled 27. My wedding ring ______ yellow and white gold. A. is made B. is making C. made D. make 28. Mr. Wilson is _______ as Willie to his friend. A. known B. knew C. is known D. know 29. References _____ in the examination room. A. not are used B. is not used C. didn’t used D. are not used 30. Laura ______ in Boston. A. are born B. were born C. was born D. born 31. His car needs ________. A. be fixed B. fixing C. to be fixing D. fixed 32. Her watch needs _______. A. repairing B. to be repaired C. repaired D. A and B 33. My mother is going _____ this house. A. sold B. sell C. to be sold D. to sell 34. There’s somebody behind us. I think we are _______. A. being followed B. are followed C. follow D. following 35. Have you _____ by a dog?A. bite B. bit C. ever been bitten D. ever been bit 36. The room is being _____ at the moment. A. was cleaned B. cleaned C. cleaning D. clean 37. It _____ that the strike will end soon. A. is expected B. expected C. are expected D. was expected 38. It is _____ that many people are homeless after the floods. A. was reported B. reports C. reported D. reporting 39. He was said _____ this building. A. designing B. to have designed C. to design D. designed 40. Ted ______ by a bee while he was sitting in the garden. A. got sting B. got stung C. get stung D. gets stung 41. These tennis courts don’t _____ very often. Not many people want to play. A. got used B. used C. get used D. get use 42. I’ll get Minh _____ do this for you. A. do B. done C. did D. to do 43. Those letters ________ now. You can do the typing later. A. need typing B. needn't be typed C. need to type D. needn't typing 44. “What a beautiful dress you are wearing”- “thanks, it_____ especially for me by a French tailor.” A. is made B. has made C. made D. was made 45. Somebody cleans the room every day. A. The room everyday is cleaned. B. The room is every day cleaned. C. The room is cleaned every day. D. The room is cleaned by somebody every day. 46. People don’t use this road very often. A. This road is not used very often. B. Not very often this road is not used. C. This road very often is not used. D. This road not very often is used. 47. How do people learn languages? A. How are languages learned? B. How are languages learned by people? C. How languages are learned? D. Languages are learned how? 48. Over 1500 new houses _______ each year. Last year, 1720 new houses _______. A. were built/ were built B. are built/ were built C. are building / were built D. were built/ were being built 49. Tom bought that book yesterday. A. That book was bought by Tom yesterday. B. That book was bought yesterday by Tom. C. That book yesterday was bought by Tom D. That book was bought yesterday. 50. The new computer system _____ next month. A. is be installed B. is being installed C. is been installed D. is being installed by people CHUYÊN ĐỀ 4: CÂU ĐIỀU KIỆN 1. “Would you mind if we ___you by your first name?” “Not at all. Please call me Tom.” A. called B. call C. calling D. want to call 2. She can’t get home ___ she has no money. A. unless B. if C. until D. without 3. If I had known your new address, we ___to see you. A. came B. will come C. would come D. would have come 4. If we took the 10:30 train, ___. A. we would arrive too early B. we should arrive too early C. we will arrive too early D. we may arrive too early 5. It’s very crowded here. I wish there ___ so many people. A. aren’t B. weren’t C. haven’t been D. isn’t 6. I wouldn’t go there at night if I ___ you. A. am B. was C. were D. had been 7. If I ___ get a pole, I’ll go fishing. A. can B. could C. may D. might 8. If they had enough time, they ___ head south. A. will B. can C. must D. might 9. If you ___ a choice, which country would you visit? A. have B. had C. have had D. will have 10. Trees won’t grow ___ there is enough water. A. if B. when C. unless D. as 11. ___ she agreed, you would have done it. A. If B. Had C. Should D. Would 12. If you ___ to be chosen for the job, you’ll have to be experienced in the field. A. want B. wanted C. had wanted D. wants 13. If the doctor had arrived sooner, the boy ___. A. might be saved B. have been saved C. was saved D. might have been saved 14. If there ___, the rice fields could have been more productive. A. had been enough water B. were enough water C. would be enough water D. are enough water 15. The patient could not recover unless he ___ an operation. A. had undergone B. would undergo C. underwent D. was undergoing 16. If she ___ him, she would be very happy. A. would meet B. will meet C. is meeting D. should meet 17. If he ___ a thorough knowledge of English, he could have applied for this post. A. had had B. had C. has D. has had 18. If I had enough money, I ___ abroad to improve my English. A. will go B. would go C. should go D. should have to go 19. If it ___ convenient, let’s go out for a drink tonight. A. be B. is C. was D. were 20. If you ___ time, please write to me. A. have B. had C. have had D. has 21. If it ___ tomorrow, we may postpone going on a picnic. A. rains B. will rain C. shall rain D. raining 22. If you hadn’t watched that late mivie last night, you ___ sleepy now. A. wouldn’t have been B. wouldn’t be C. might have not been D. wouldn’t have been being 23. If you ___ as I told you, you ___ sorry now. A. did- would not be B. had done- had not been C. do – would not beD. had done – would not be 24. If only I ___ him now. A. see B. saw C. have seen D. seen 25. If I ___, I’ll let you know. A. am staying B. will stay C. do stay D. would stay 26. If only I ___ you wanted to invest money in business. A. had known B. knew C. have known D. know 27. Linda wishes she ___her car. A. hasn’t sold B. hadn’t sold C. doesn’t sell D. won’t sell 28. He looked frightened as if he___a ghost. A. had seen B. saw C. would see D. was seeing 29. I wish it ___ a holiday today.A. were B. will be C. is D. had been 30. “My car broke down when I was leaving Detroit and I had to take the bus.” “___, we would have picked you up.” A. Had we known B. If we have known C. We had known D. If we did know 31. If I ___ as young as you are, I ___ in a boat round the world. A. were- would sail B. would be – would sail C. were- will sail D. would- would sail 32. If he___tickets yesterday, he ___ on the beach now. A. had booked- would be lying B. had booked- would have lied C. booked – would lie D. books- will lie 33. If you ___ less last night, you ___ so bad today. A. had drunk- would not have felt B. drank- would not feel C. had drunk- would not feel D. would have drunk- would not feel 34. It seemed as if he ___ of it before. A. would never hear B. has never heard C. never heard D. had never heard 35. ___ today, she would get home by Friday. A. Would she leave B. Was she leaving C. Were she to leave D. If she leaves 36. “He’s a very brave man.” “Yes, I wish I ___ his courage.” A. have B. had C. will have D. would have 37. ___he___ hard last year, he would have lost the first prize. A. Hadn’t – studied B. Had- studied C. Didn’t study D. If – had studied 38. We’re going to be late if ___. A. we not leave right now B. we didn’t leave right now C. we won’t leave right now D. we don’t leave right now 39. “I wish this city___ so noisy.” “I know. I wish we ___ in the countryside.” A. isn’t – live B. wasn’t – live C. weren’t- live D. weren’t – lived 40. He acted as though he___ for days. A. not eat B. hasn’t eaten C. hadn’t eaten D. didn’t eat 41. We ___ the game if we’d had a few more minutes. A. might have won B. won C. had won D. will win 42. I ___ William with me if I had known you and he didn’t get along with each other. A. hadn’t brought B. didn’t bring C. wouldn’t have brought D. won’t bring 43. If you ___ to my advice in the first place, you wouldn’t be in this mess right now. A. listen B. will listen C. had listened D. listened 44. ___ interested in that subject, I would try to learn more about it. A. Were I B. Should I C. I was D. If I am 45. I ___ you sooner had someone told me you were in the hospital. A. would have visited B. visited C. had visited D. visit 46. ___ then what I know today, I would have saved myself a lot of time and trouble over the years. A. Had I known B. Did I know C. If I know D. If I would know CHUYÊN ĐỀ 5: CÂU GIÁN TIẾP 1. Julia said that she ___________ there at noon. A. is going to be B. was going to be C. will be D. can be 2. He _______ that he was leaving way that afternoon. A. told me B. told to me C. said me D. says to me 3. She said to me that she __________ to me the Sunday before. A. wrote B. has written C. was writing D. had writing 4. I _________ him to sell that old motorbike. A. said to B. suggested C. advised D. recommended 5. My parents reminded me ________ the flowers. A. remember to plant B. not to plant to plant C. to plant D. planting 6. I asked Martha ______ to enter law school. A. are you planning B. is she planning C. was she planning D. if she was planning 7. Nam wanted to know what time ________. A. does the movie begin B. did the movie begin C. the movie begins D. the movie began 8. I wondered_______ the right thing. A. whether I was doing B. if I am doing C. was I doing D. am I doing 9. The scientist said the earth ________ the sun. A. goes around B. is going around C. went around D. was going around 10. Peter said that if he ________rich, he _________ a lot. A. is – will travel B. were – would travel C. had been – would have travelled D. was – will travel 11. They said that they had been driving through the desert__________. A. the previous day B. yesterday C. the last day D. Sunday previously 12. He asked the children _________too much noise. A. not to make B. not making C. don’t make D. if they don’t make 13. The man said that the days _________longer in summer. A. will be B. are C. were D. can be 14. The teacher said Columbus _________America in 1942. A. discovered B. had discovered C. was discovering D. would discover 15. John said he _________ her since they ________ school. A. hasn’t met – left B. hadn’t met - had left C. hadn’t met – left D. didn’t meet – has left 16. The woman asked __________get lunch at school. A. can the children B. whether the children could C. if the children can D. could the children 17. Laura said that when she_________ to school, she saw an accident. A. was walking B. has walked C. had been walking D. has been walking 18.
Tài liệu đính kèm: