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1、雅思阅读考前模拟试题（4套）（1）★TimetocoolitDec13th2006FromTheEconomistprintedition 1REFRIGERATORSaretheepitomeofclunkytechnology:solid,reliableandjustalittlebitdull.Theyhavenotchangedmuchoverthepastcentury,butthentheyhavenotneededto.Theyarebasedonarobustandeffectiveidea--drawheatfromthethingy
2、ouwanttocoolbyevaporatingaliquidnexttoit,andthendumpthatheatbypumpingthevapourelsewhereandcondensingit.Thismethodofpumpingheatfromoneplacetoanotherservedmankindwellwhenrefrigerators'mainjobswerepreservingfoodand,asairconditioners,coolingbuildings.Today'shigh-techworld,however,dem
3、andshigh-techrefrigeration.Heatpumpsarenolongeruptothejob.Thesearchisonforsomethingtoreplacethem.2 Onesetofcandidatesareknownasparaelectricmaterials.Theseactlikebatterieswhentheyundergoatemperaturechange:attachelectrodestothemandtheygenerateacurrent.Thiseffectisusedininfra-redca
4、meras.Anarrayoftinypiecesofparaelectricmaterialcansensetheheatradiatedby,forexample,aperson,andthepatternofthearray'selectricaloutputscanthenbeusedtoconstructanimage.Butuntilrecentlynoonehadbotheredmuchwiththeinverseofthisprocess.Thatinverseexists,however.Applyanappropriatecurren
5、ttoaparaelectricmaterialanditwillcooldown.3 SomeonewhoislookingatthisinverseeffectisAlexMischenko,ofCambridgeUniversity.Usingcommerciallyavailableparaelectricfilm,heandhiscolleagueshavegeneratedtemperaturedropsfivetimesbiggerthananypreviouslyrecorded.Thatmaybeenoughtochangetheph
6、enomenonfromalaboratorycuriositytosomethingwithcommercialapplications.4 Astowhatthoseapplicationsmightbe,DrMischenkoisstillalittlehazy.Hehas,nevertheless,setupacompanytopursuethem.Heforeseesputtinghisdiscoverytouseinmoreefficientdomesticfridgesandairconditioners.Therealmoney,tho
7、ugh,maybeincoolingcomputers.5Gadgetscontainingmicroprocessorshavebeengettinghotterforalongtime.OneconsequenceofMoore'sLaw,whichdescribesthedoublingofthenumberoftransistorsonachipevery18months,isthattheamountofheatproduceddoublesaswell.Infact,itmorethandoubles,becausebesidesincrea
8、singinnumber,thecomponentsaregettingfast
