2019年雅思阅读考试模拟试练习题及答案解析.docx

1、2019年雅思阅读考试模拟试练习题及答案解析Time to cool itFrom The Economist print edition1 REFRIGERATORS are the epitome of clunky technology： solid, reliable and just a little bit dull. They have not changed much over the past century, but then they have not needed to. They are based on a robust and effective idea-dra

2、w heat from the thing you want to cool by evaporating a liquid next to it, and then dump that heat by pumping the vapour elsewhere and condensing it. This method of pumping heat from one place to another served mankind well when refrigerators main jobs were preserving food and, as air conditioners,

3、cooling buildings. Todays high-tech world, however, demands high-tech refrigeration. Heat pumps are no longer up to the job. The search is on for something to replace them.2 One set of candidates are known as paraelectric materials. These act like batteries when they undergo a temperature change： at

4、tach electrodes to them and they generate a current. This effect is used in infra-red cameras. An array of tiny pieces of paraelectric material can sense the heat radiated by, for example, a person, and the pattern of the arrays electrical outputs can then be used to construct an image. But until re

5、cently no one had bothered much with the inverse of this process. That inverse exists, however. Apply an appropriate current to a paraelectric material and it will cool down.3 Someone who is looking at this inverse effect is Alex Mischenko, of Cambridge University. Using commercially available parae

6、lectric film, he and his colleagues have generated temperature drops five times bigger than any previously recorded. That may be enough to change the phenomenon from a laboratory curiosity to something with commercial applications.4 As to what those applications might be, Dr Mischenko is still a lit

7、tle hazy. He has, nevertheless, set up a company to pursue them. He foresees putting his discovery to use in more efficient domestic fridges and air conditioners. The real money, though, may be in cooling computers.5 Gadgets containing microprocessors have been getting hotter for a long time. One co

8、nsequence of Moores Law, which describes the doubling of the number of transistors on a chip every 18 months, is that the amount of heat produced doubles as well. In fact, it more than doubles, because besides increasing in number, the components are getting faster. Heat is released every time a log

9、ical operation is performed inside a microprocessor, so the faster the processor is, the more heat it generates. Doubling the frequency quadruples the heat output. And the frequency has doubled a lot. The first Pentium chips sold by Dr Moores company, Intel, in 1993, ran at 60m cycles a second. The

10、Pentium 4-the last single-core desktop processor-clocked up 3.2 billion cycles a second.6 Disposing of this heat is a big obstruction to further miniaturisation and higher speeds. The innards of a desktop computer commonly hit 80. At 85, they stop working. Tweaking the processors heat sinks (copper

11、or aluminium boxes designed to radiate heat away) has reached its limit. So has tweaking the fans that circulate air over those heat sinks. And the idea of shifting from single-core processors to systems that divided processing power between first two, and then four, subunits, in order to spread the

12、 thermal load, also seems to have the end of the road in sight.7 One way out of this may be a second curious physical phenomenon, the thermoelectric effect. Like paraelectric materials, this generates electricity from a heat source and produces cooling from an electrical source. Unlike paraelectrics

13、, a significant body of researchers is already working on it.8 The trick to a good thermoelectric material is a crystal structure in which electrons can flow freely, but the path of phonons-heat-carrying vibrations that are larger than electrons-is constantly interrupted. In practice, this trick is

14、hard to pull off, and thermoelectric materials are thus less efficient than paraelectric ones (or, at least, than those examined by Dr Mischenko). Nevertheless, Rama Venkatasubramanian, of Nextreme Thermal Solutions in North Carolina, claims to have made thermoelectric refrigerators that can sit on

15、the back of computer chips and cool hotspots by 10. Ali Shakouri, of the University of California, Santa Cruz, says his are even smaller-so small that they can go inside the chip.9 The last word in computer cooling, though, may go to a system even less techy than a heat pump-a miniature version of a

16、 car radiator. Last year Apple launched a personal computer that is cooled by liquid that is pumped through little channels in the processor, and thence to a radiator, where it gives up its heat to the atmosphere. To improve on this, IBMs research laboratory in Zurich is experimenting with tiny jets

17、 that stir the liquid up and thus make sure all of it eventually touches the outside of the channel-the part where the heat exchange takes place. In the future, therefore, a combination of microchannels and either thermoelectrics or paraelectrics might cool computers. The old, as it were, hand in ha

18、nd with the new.(830 words)Questions 1-5Complete each of the following statements with the scientist or company name from the box below.Write the appropriate letters A-F in boxes 1-5 on your answer sheet.A. AppleB. IBMC. IntelD. Alex MischenkoE. Ali ShakouriF. Rama Venkatasubramanian1. .and his rese

19、arch group use paraelectric film available from the market to produce cooling.2. .sold microprocessors running at 60m cycles a second in 1993.3. .says that he has made refrigerators which can cool the hotspots of computer chips by 10.4. .claims to have made a refrigerator small enough to be built in

20、to a computer chip.5. .attempts to produce better cooling in personal computers by stirring up liquid with tiny jets to make sure maximum heat exchange.Questions 6-9Do the following statements agree with the information given in the reading passage?In boxes 6-9 on your answer sheet writeTRUE if the

21、statement is true according to the passageFALSE if the statement is false according to the passageNOT GIVEN if the information is not given in the passage6. Paraelectric materials can generate a current when electrodes are attached to them.7. Dr. Mischenko has successfully applied his laboratory dis

22、covery to manufacturing more efficient referigerators.8. Doubling the frequency of logical operations inside a microprocessor doubles the heat output.9. IBM will achieve better computer cooling by combining microchannels with paraelectrics.Question 10Choose the appropriate letters A-D and write them

23、 in box 10 on your answer sheet.10. Which method of disposing heat in computers may have a bright prospect?A. Tweaking the processors?heat sinks.B. Tweaking the fans that circulate air over the processor抯 heat sinks.C. Shifting from single-core processors to systems of subunits.D. None of the above.

24、Questions 11-14Complete the notes below.Choose one suitable word from the Reading Passage above for each answer.Write your answers in boxes 11-14 on your answer sheet.Traditional refrigerators use.11.pumps to drop temperature. At present, scientists are searching for other methods to produce refrige

25、ration, especially in computer microprocessors.12.materials have been tried to generate temperature drops five times bigger than any previously recorded. .13.effect has also been adopted by many researchers to cool hotspots in computers. A miniature version of a car .14. may also be a system to real

26、ize ideal computer cooling in the future.Key and Explanations：1. DSee Paragraph 3： .Alex Mischenko, of Cambridge University. Using commercially available paraelectric film, he and his colleagues have generated temperature drops.2. CSee Paragraph 5： The first Pentium chips sold by Dr Moores company,

27、Intel, in 1993, ran at 60m cycles a second.3. FSee Paragraph 8： .Rama Venkatasubramanian, of Nextreme Thermal Solutions in North Carolina, claims to have made thermoelectric refrigerators that can sit on the back of computer chips and cool hotspots by 10.4. ESee Paragraph 8： Ali Shakouri, of the Uni

28、versity of California, Santa Cruz, says his are even smaller梥o small that they can go inside the chip.5. BSee Paragraph 9： To improve on this, IBMs research laboratory in Zurich is experimenting with tiny jets that stir the liquid up and thus make sure all of it eventually touches the outside of the

29、 channel-the part where the heat exchange takes place.6. TRUESee Paragraph 2： .paraelectric materials. These act like batteries when they undergo a temperature change： attach electrodes to them and they generate a current.7. FALSESee Paragraph 3 (That may be enough to change the phenomenon from a la

30、boratory curiosity to something with commercial applications. ) and Paragraph 4 (As to what those applications might be, Dr Mischenko is still a little hazy. He has, nevertheless, set up a company to pursue them. He foresees putting his discovery to use in more efficient domestic fridges?8. FALSESee

31、 Paragraph 5： Heat is released every time a logical operation is performed inside a microprocessor, so the faster the processor is, the more heat it generates. Doubling the frequency quadruples the heat output.9. NOT GIVENSee Paragraph 9： In the future, therefore, a combination of microchannels and

32、either thermoelectrics or paraelectrics might cool computers.10. DSee Paragraph 6： Tweaking the processors heat sinks ?has reached its limit. So has tweaking the fans that circulate air over those heat sinks. And the idea of shifting from single-core processors to systems?also seems to have the end

33、of the road in sight.11. heatSee Paragraph 1： Todays high-tech world, however, demands high-tech refrigeration. Heat pumps are no longer up to the job. The search is on for something to replace them.12. paraelectricSee Paragraph 3： Using commercially available paraelectric film, he and his colleague

34、s have generated temperature drops five times bigger than any previously recorded.13. thermoelectricSee Paragraph 7： .the thermoelectric effect. Like paraelectric materials, this generates electricity from a heat source and produces cooling from an electrical source. Unlike paraelectrics, a significant body of researchers is already working on it.14. radiatorSee Paragraph 9： The last word in computer cooling, though, may go to a system even less techy than a heat pump-a miniature version of a car radiator.