《雅思阅读模拟试题和答案(共10页)》由会员分享，可在线阅读，更多相关《雅思阅读模拟试题和答案(共10页)（10页珍藏版）》请在金锄头文库上搜索。
1、精选优质文档-倾情为你奉上雅思阅读模拟试题和答案众多考鸭面对雅思阅读最头疼的问题就是时间来不及，雅思阅读模拟题专为你而来，阅读材料皆为雅思真题素材的重要来源如：经济学人、新科学家等等，精读及练习题，更有题目详解为你答疑解惑。坚持每日一练，考场上就是这么自信。带来今日每日晨读之Time to cool it,文章摘自经济学人（The Economist），所有方法技巧都需要反复做题去巩固，自己不足的地方也只有通过做题才能显现。练习也是有技巧的，不能盲目瞎做。把每一次阅读练习都当做考试，时间一个小时，三篇阅读，没有手机，没有字典，没有参考资料，没有笔记。只有这样，在考场上才有可能在50分钟内做完题
2、目(十分钟的誊写答案以及检查时间)。1.雅思阅读材料1 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 andidea-draw heat from the thing you want to cool by evaporating
3、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, cooling buildings. Todays high-tech world, however, de
4、mands 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: attach electrodes to them and they generate a current. T
5、his 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 recently no one had bothered much with the inverse of th
6、is 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 paraelectric film, he and his colleagues have generated tem
7、perature 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 little hazy. He has, nevertheless, set up a company to pu
8、rsue them. He foresees putting his discovery to use in moredomestic 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 consequence of Moores Law, which describes the doubling of the numb
9、er 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 logical operation is performed inside a microprocessor, so the faste
10、r 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 Pentium 4-the last single-core desktop processor-clocked up 3.2 b
11、illion 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 or aluminium boxes designed to radiate heat away) has reached its
12、 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 thermal load, also seems to have the end of the road in sight.7
13、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, a significant body of researchers is already working on it.8 Th
14、e 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 hard to pull off, and thermoelectric materials are thus less effi
15、cient 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 the back of computer chips and cool hotspots by 10. Ali Shakouri,
16、 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 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 atm
