12x^2+30x-21/16x^2-9 - 3x-7/3-4x=6x+5/4x+3

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I. Choose the word or phrase (A, B, C or D) that best fits the blank space in the following passage.                 In recent years there have been many (1) ________ on air pollution in newspapers and magazines. Scientists all over the world have warned that our atmosphere is (2) ________ more and more contaminated, and that Man, through his carelessness, may run (3) ____________ of pure air to breathe.                 Automobiles and industries mainly (4) ________ for air pollution in most cities. They pure into the air such gases as carbon monoxide, sulphur and nitrogen oxides, which are very (5) ________ to humans. Worse still, these gases after a series of chemical changes, turn (6) ________ toxic acids. They fall down in ‘acid rain’, raising the acidity in the air, soil and water to dangerous (7) ____________and affecting not only trees but also fish and other wildlife. Many industrial countries in Europe and North America have (8) ________ bad affects from those ‘rains’.                 (9) ________, man faces no more urgent problem than that of saving his own survival. Scientists, social organization and governments should sit down together to solve the air (10) ________ problem. 1. A. programs             B. events   C. articles                            D. columns 2.            A. changing             B. becoming      C. making                            D. taking 3.            A. up        B. over                                 C. away                  D. out 4.            A. bring        B. get                                     C. account                           D. count 5.            A. harmful             B. powerful                        C. awful                               D. painful 6.            A. in              B. into                                   C. out                                    D. over 7.            A. amounts      B. ranks                               C. points                              D. levels 8.            A. suffered        B. influenced                     C. offered                            D. bothered 9.            A. Naturally        B. Safely                              C. Surely                              D. Practically 10.          A. pollute               B. polluted                          C. polluting                         D. pollution

Giups mình zới --Vote 5 sao và bình chọn cho câu trả lời hay nhất nè--- 1)There __________ 54 ethnic minorities in Viet Nam. A. is B. are C. was D. were 2)Robert ________ tomorrow morning on the 10:30 train. A. arrived B. is arriving C. has arrived D. would arrive 3)I will come and see you before I _________ for America. A. leave B. will leave C. have left D. shall leave 4) I __________ along the road when I saw Dave, so I stopped and we had a chat. A. walked B. am walking C. was walking D. walk 5) This time last year, I ____________ in France. A. was living B. am living C. lived D. had lived 6) He _______ in the bank for five years. A. had worked B. has worked C. worked D. works 7) Angelina Jolie is a famous actress. She ________ in several film. A. appears B. is appearing C. appeared D. has appeared 8) We________ this course before the final examination. A. are going to finish B. have finished C. will finish D. finished 9) While I ________ cakes, my sister ________ her homework. A. was eating/ did B. ate/ did C. ate/ was doing D. was eating/ was doing 10) She __________ in the library last night. A. had studied B. has studied C. studied D. studies 11) My teacher often ________ to work by bus in the afternoon. A. is working B. worked C. will work D. works 12) Look! The bus _____________ . A. left B. has left C. leaves D. is leaving 13) “Would you like something to eat?” - “ No, thank you. I __________ lunch.” A. have just had B. just have had C. had just had D. just had had 14)I think she ________ as soom as she knows the news. A. leaves B. is going to leave C. will leave D. had left 15) Mr. Smith _______ with his cast in the studio at the moment. A. works B. is working C. worked D. has worked 16) He has been selling motorcycles ____________. A. ten years ago B. for ten years C. for ten years ago D. since ten years 17) “Why are you turning on the television?” - “ I __________ the news.” A. watch B. will watch C. am going to watch D. watched 18) While her husband was in the army, Janet________ to him twice a week. A. was writing B. wrote C. was written D. had written 19) He will take the dog out for a walk as soon as he ________ dinner. A. finishes B. finish C. will finish D. is finishing 20) The Olympic Games ________ every four years. A. take place B. takes place C. took place D. is taking place 21) After I _____ my colors, I ______ to paint. A. had mixed/ started B. mixed/ had started C. mixed/ started D. had mixed/ had started 22) What time________ the next train leave? A. does B. will C. shall D. would 23) The art exhibition ______ on 3 May and ______ on 15 July. A. opened/ finished B. will open/ will finish C. opens/ finishes D. open/ finish 24) George ________ off the ladder while he was painting the ceiling. A. falls B. fell C. has fallen D. was falling 25) I ________ anything yesterday because I __________ hungry. A. don’t eat/ don’t feel B. haven’t eaten/ haven’t felt C. didn’t eat/ didn’t feel D. hadn’t eaten/ hadn’t felt 26) My friend _________ to see me yesterday. C. has come B. came D. will come A. comes 27) The Perfume River __________ through Hue City. A. flow B. flew C. is flowing D. flows 28)They __________ in a few minutes. A. arrive B. are going to arrive C. will arrive D. are arriving 29) Mai and Lan _______ pen pals for over two years. A. has been B. have been C. has known D. have known 30) Look! It __________ at present. A. rains B. is raining C. will rain D. rained