english 4 bkfwqgh31gứa;;kfaqưkgkwq gưd fskfs sakfảowjfiwjjfwkfsdhfshfsơjbfjwbsamkeqjkkfnadohfu0wqhnưkdfnksf0hưeuwbưdbjsbjdjfjdnfmmqkkamdmakdạiahfan;ầhuqhbfjbfr ưueh ưhưhhfhf;shfjdhjfhshfuhùuwsfbsds Trong mạch có 2 chân đầu ra là Aout và Dout. Trong đó: o Aout: điện áp ra tương tự. Nó chạy từ 0.3à4.5V, phụ thuộc vào nồng độ khí xung quang MQ2. o Dout: điện áp ra số, giá trị 0,1 phụ thuộc vào điện áp tham chiếu và nồng độ khí mà MQ2 đo được. o Việc có chân ra số Dout rất tiện cho ta mắc các ứng dụng đơn giản, không cần đến vi điều khiển. Khi đó ta chỉ cần chỉnh giá trị biến trở tới giá trị nồng độ ta muốn cảnh báo. Khi nồng độ MQ2 đo được thấp hơn mức cho phép thì Dout = 1. Đèn Led tắt. Khi nồng độ khí đo được lớn hơn nồng khí cho phép, Dout =0, đèn led sáng. o Ta có thể ghép nối vào mạch Realy để điều khiển bật tắt đèn, còi, hoặc thiết bị cảnh báo khác. Một điều khó khăn khi làm việc với MQ2 là chúng ta khó có thể quy từ điện áp Aout về giá trị nồng độ ppm. Rồi từ đó hiển thị và cảnh báo theo ppm. Do giá trị điện áp trả về từng loại khí khác nhau, lại bị ảnh hưởng nhiệt độ, độ ẩm nữa. Trong thiết bị của mình, để xác định điểm cảnh báo mình làm khá thủ công. o Đầu tiên đo trạng thái không khí sạch, giá trị thu được Vout1 o Cho khí ga từ bật lửa rò rỉ ra. Ta thấy giá trị Aout tăng lên. Khi đạt khoảng cách khí ga từ bật lửa hợp lý rồi tương ứng với nồng độ khí bắt đầu nguy hiểm, ta ghi lại giá trị Vout2. Ta chọn giá trị Vout2 là giá trị ngưỡng cảnh báo. Nếu giá trị đo được lớn hơn ta sẽ cảnh báo o Chỉnh chân biến trở để điện áp đo tại chân 3 của L358 = Vout2. Mình viết code trên Atmega8, anh em tham khảo nha.
Bach Khoa University – Foreign Language Center lequangthao2410@gmail.com Name: _ PRACTICE TEST – UNIT 789 PRONUNCIATION: Choose the word whose underlined part is pronounced differently from that of the others: A heart B earn C search D researcher A practices B washes C loves D misses A prevent B strengthen C objection D debate A wicked B looked C hoped D danced A exhilarating B humorous C hose D hilly Choose the word whose main stress is different from that of the others: A convey B influx C conflict D even A authority B transportation C alternative D pedestrian A degrade B lightweight C evolve D unique A represent B unsustainable C understand D rechargeable 10 A suitable B portable C fantastic D comfortable GRAMMAR, VOCABULARY & STRUCTURES: Choose the best answer to complete each of the following sentences: 11 _A: So, how are you finding life here? _B: Oh, it’s great But I a job A haven’t still found B haven’t still been finding C still haven’t found D still haven’t been finding 12 In distant future, space travel affordable for many people A might be going to B is going to be C will be able D won’t be going to be 13 People waiter for men and waitress for women, but now many people server for both A used to say, said B said, have been said C used to say, say D didn’t use to say, have said 14 Space vacations by 2025 Scientists still have many difficulties understanding the universe A will absolutely be possible B might not be possible C might be happen D may not be exist 15 Due to the influence of globalization and internet, more and more people English words to communicate A used PRACTICE TEST (Unit 789) B used to use C are using D have been used Page of Bach Khoa University – Foreign Language Center lequangthao2410@gmail.com 16 _A: How long for a job? _B: A couple of months now I think I 10 applications this week alone A have you been looking, have sent B have you looked, have been sending C have you looked, am sending D have you been looking, have been sending 17 He hasn’t been able to in a big city It’s much more difficult and he always feels homesick A get used to living B get used to C be used to D getting used to living 18 I’m sure the price of oil over the next few years A may rise B be going to rise C will rise D might be rising 19 When I was studying Spanish, I down a few new words to learn every day A used to write B used to writing C got used to write D did use to writing 20 There high-speed long-distance trains underground in the future A will have B may have C might be having D will be 21 Before the Internet, people access to so much information A used to have B didn’t use to be C used to be D didn’t use to have 22 Some changes in language noticeable because they over hundreds of year A are, happened B are not, happen C have not been, had happened D is not, have happened 23 Your sense identity is how you feel yourself A about, of B of, about C in, of D of, on 24 If I’m not stuck traffic, traveling bus takes me about 60 minutes door door A in, with, by B with, by, to C into, on, from D in, by, to 25 He has no objections the fact that students are banned using slang in schools A from, on B of, from C to, from D from, to 26 There can sometimes be misunderstandings between people of different ethnic backgrounds that result in A conflicts B identity C interactions D communications 27 Economic migrants look overseas for better work _and an improved standard of living A chancing B change C diversity D opportunities 28 Some people feel that the use of slang should be A rapidly B conveyed C banned D expressed 29 Dictionary editors study data on the and popularity of new words A robust B usage C remains D hose 30 The word frenemy its meaning more quickly than standard language A interacts B repairs C changes D conveys 31 The of migrants around the world is not even UAE is one of the top destinations for migrants A distribution PRACTICE TEST (Unit 789) B footprints C transportation D change Page of Bach Khoa University – Foreign Language Center lequangthao2410@gmail.com 32 With the interaction of people all over the world, we are able to experience a(n) range of cultures and customs A noticeable B diverse C suitable D vibrant 33 New York City, also known as “the melting pot”, is one of the most _ cities in the world A sustainable B maneuverable C multi-cultural D guaranteed 34 There is a(n) of tourists every year in the summer This is the time when most people like spending their vacation A vibrancy B influx C evolution D immigrant 35 People who by bus or train might have difficulty with walking long distances to the bus stops A usage B get C catch D commute 36 In today’s highly connected world, slang has become more because of better tools to observe language change A portable B noticeable C exhilarating D diversity 37 The use of slang people to communicate complex ideas effectively A makes B allow C enables D lets 38 Electric are not as fast as fuel-powered cars, but they are better for the environment A traffic B vehicles C solutions D commutes 39 The train was so packed this morning that I couldn’t I had to wait for the next one A get off B get out of C get on D travel 40 The internet has resulted in new methods of learning and communication that were previously A alternative B multi-cultural C traditional D unimaginable 41 As cities have grown in size and population, scientists have come up with ways to improve systems A degrading B standard change C modes D public transportation 42 Giant buses that drive over cars are an interesting means of transport which reduces congestion A alternative B economic C undertaking D portable 43 Since this vehicle solar power and electricity, it helps to reduce pollution A charges B runs on C powers of D recharges 44 We can reduce our by walking or taking a public transportation A carbon footprint B energy C modes D being rechargeable 45 The introduction of new words can help the language A charge PRACTICE TEST (Unit 789) B strengthen C accept D defriend Page of Bach Khoa University – Foreign Language Center lequangthao2410@gmail.com CLOZE PASSAGE Read the passage and choose the best answer to fill in each blank Slang refers to words, phrases and uses that are (46) as very informal and often restricted to special context or peculiar to a specified profession class and the like Slang words (47) in specific social groups, like teenagers In its earliest attested use (1756), the word slang referred to the vocabulary of "low or disreputable" people By the early nineteenth century, it was no longer exclusively associated with disreputable people, but continued to be applied to language use below the level of (48) educated speech The origin of the word is uncertain, although it appears (49) _connected with thieves' cant A Scandinavian origin has been proposed (compare, for example, Norwegian slengenavn, which means "nickname"), but is discounted by the Oxford English Dictionary based on "date and early associations" Jonathan Green however agrees with the possibility of a Scandinavian origin, suggesting the same root as that of sling, which means "to throw", and (50) _that slang is a thrown language - a quick, honest way to make your point 46 A considered B regarded C looked D seeing 47 A are used B are using C have used D can be usage 48 A guaranteed B customized C standard D informal 49 A being B be C to being D to be 50 A noting B note C noted D to note THE END PRACTICE TEST (Unit 789) Page of