雅思备考实战模拟训练试题.docx

雅思备考实战模拟训练试题2017雅思备考实战模拟训练试题雅思类似与中国的高考，是申请英语国家高校必须提供的'成绩单。以下是百分网小编精心为大家整理的雅思备考实战模拟训练试题，希望对大家有所帮助!更多内容请关注应届毕业生网!FromTheEconomistprintedition1REFRIGERATORSaretheepitomeofclunkytechnology:solid,reliableandjustalittlebitdull.Theyhavenotchangedmuchoverthepastcentury,butthentheyhavenotneededto.Theyarebasedonarobustandeffectiveidea--drawheatfromthethingyouwanttocoolbyevaporatingaliquidnexttoit,andthendumpthatheatbypumpingthevapourelsewhereandcondensingit.Thismethodofpumpingheatfromoneplacetoanotherservedmankindwellwhenrefrigerators'mainjobswerepreservingfoodand,asairconditioners,coolingbuildings.Today'shigh-techworld,however,demandshigh-techrefrigeration.Heatpumpsarenolongeruptothejob.Thesearchisonforsomethingtoreplacethem.2Onesetofcandidatesareknownasparaelectricmaterials.Theseactlikebatterieswhentheyundergoatemperaturechange:attachelectrodestothemandtheygenerateacurrent.Thiseffectisusedininfra-redcameras.Anarrayoftinypiecesofparaelectricmaterialcansensetheheatradiatedby,forexample,aperson,andthepatternofthearray'selectricaloutputscanthenbeusedtoconstructanimage.Butuntilrecentlynoonehadbotheredmuchwiththeinverseofthisprocess.Thatinverseexists,however.Applyanappropriatecurrenttoaparaelectricmaterialanditwillcooldown.3SomeonewhoislookingatthisinverseeffectisAlexMischenko,ofCambridgeUniversity.Usingcommerciallyavailableparaelectricfilm,heandhiscolleagueshavegeneratedtemperaturedropsfivetimesbiggerthananypreviouslyrecorded.Thatmaybeenoughtochangethephenomenonfromalaboratorycuriositytosomethingwithcommercialapplications.4Astowhatthoseapplicationsmightbe,DrMischenkoisstillalittlehazy.Hehas,nevertheless,setupacompanytopursuethem.Heforeseesputtinghisdiscoverytouseinmoreefficientdomesticfridgesandairconditioners.Therealmoney,though,maybeincoolingcomputers.5Gadgetscontainingmicroprocessorshavebeengettinghotterforalongtime.OneconsequenceofMoore'sLaw,whichdescribesthedoublingofthenumberoftransistorsonachipevery18months,isthattheamountofheatproduceddoublesaswell.Infact