雅思真题原文Word下载.docx

雅思真题原文Word下载.docx

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Materialsforlecture16-18

Readingpassage1

Questions1-13arebasedonthefollowingpassage.

Sheetglassmanufacture:

thefloatprocess

Glass,whichhasbeenmadesincethetimeoftheMesopotamiansandEgyptians,islittlemorethanamixtureofsand,sodaashandlime.Whenheatedtoabout1500degreesCelsius（°

C）thisbecomesamoltenmassthathardenswhenslowlycooled.Thefirstsuccessfulmethodformakingclear,flatglassinvolvedspinning.Thismethodwasveryeffectiveastheglasshadnottouchedanysurfacesbetweenbeingsoftandbecominghard,soitstayedperfectlyunblemished,witha‘firefinish’.However,theprocesstookalongtimeandwaslabourintensive.

Nevertheless,demandforflatglasswasveryhighandglassmakersacrosstheworldwerelookingforamethodofmakingitcontinuously.Thefirstcontinuousribbonprocessinvolvedsqueezingmoltenglassthroughtwohotrollers,similartoanoldmangle.Thisallowedglassofvirtuallyanythicknesstobemadenon-stop,buttherollerswouldleavebothsidesoftheglassmarked,andthesewouldthenneedtobegroundandpolished.Thispartoftheprocessrubbedawayaround20percentoftheglass,andthemachineswereveryexpensive.

ThefloatprocessformakingflatglasswasinventedbyAlistairPilkington.Thisprocessallowsthemanufactureofclear,tintedandcoatedglassforbuildings,andclearandtintedglassforvehicles.Pilkingtonhadbeenexperimentingwithimprovingthemeltingprocess,andin1952hehadtheideaofusingabedofmoltenmetaltoformtheflatglass,eliminatingaltogethertheneedforrollerswithinthefloatbath.Themetalhadtomeltatatemperaturelessthanthehardeningpointofglass（about600°

C）,butcouldnotboilatatemperaturebelowthetemperatureofthemoltenglass（about1500°

C）.Thebestmetalforthejobwastin.

Therestoftheconceptreliedongravity,whichguaranteedthatthesurfaceofthemoltenmetalwasperfectlyflatandhorizontal.Consequently,whenpouringmoltenglassontothemoltentin,theundersideoftheglasswouldalsobeperfectlyflat.Iftheglasswerekepthotenough,itwouldflowoverthemoltentinuntilthetopsurfacewasalsoflat,horizontalandperfectlyparalleltothebottomsurface.Oncetheglasscooledto604°

Corlessitwastoohardtomarkandcouldbetransportedoutofthecoolingzonebyrollers.Theglasssettledtoathicknessofsixmillimetresbecauseofsurfacetensioninteractionsbetweentheglassandthetin.Byfortunatecoincidence,60percentoftheflatglassmarketatthattimewasforsix-millimetreglass.

Pilkingtonbuiltapilotplantinandby1955hehadconvincedhiscompanytobuildafull-scaleplant.However,ittook14monthsofnon-stopproduction,costingthecompany£

100,000amonth,beforetheplantproducedanyusableglass.Furthermore,oncetheysucceededinmakingmarketableflatglass,themachinewasturnedoffforaservicetoprepareitforyearsofcontinuousproduction.Whenitstartedupagainittookanotherfourmonthstogettheprocessrightagain.Theyfinallysucceededin1959andtherearenowfloatplantsallovertheworld,witheachabletoproducearound1000tonsofglasseveryday,non-stopforaround15years.

Floatplantstodaymakeglassofnearopticalquality.Severalprocesses-melting,refining,homogenising-takeplacesimultaneouslyinthe2000tonnesofmoltenglassinthefurnace.Theyoccurinseparatezonesinacomplexglassflowdrivenbyhightemperatures.Itaddsuptoacontinuousmeltingprocess,lastingaslongas50hours,thatdeliversglasssmoothlyandcontinuouslytothefloatbath,andfromtheretoacoatingzoneandfinallyaheattreatmentzone,wherestressesformedduringcoolingarerelieved.

Theprincipleoffloatglassisunchangedsincethe1950s.However,theproducthaschangeddramatically,fromasinglethicknessofmmtoarangefromsub-millimetreto25mm,fromaribbonfrequentlymarredbyinclusionsandbubblestoalmostopticalperfection.Toensurethehighestquality,inspectiontakesplaceateverystage.Occasionally,abubbleisnotremovedduringrefining,asandgrainrefusestomelt,atremorinthetinputsripplesintotheglassribbon.Automatedon-lineinspectiondoestwothings.Firstly,itrevealsprocessfaultsupstreamthatcanbecorrected.Inspectiontechnologyallowsmorethan100millionmeasurementsasecondtobemadeacrosstheribbon,locatingflawstheunaidedeyewouldbeunabletosee.Secondly,itenablescomputersdownstreamtosteercuttersaroundflaws.

Floatglassissoldbythesquaremetre,andatthefinalstagecomputerstranslatecustomerrequirementsintopatternsofcutsdesignedtominimisewaste.

Questions9-13

DothefollowingstatementsagreewiththeinformationgiveninReadingPassage1?

Inboxes9-13onyouranswersheet,write

TRUEifthestatementagreeswiththeinformation

FALSEifthestatementcontradictstheinformation

NOTGIVENifthereisnoinformationonthisinthepassage

9.Themetalusedinthefloatprocesshadtohavespecificproperties.

10.Pilkingtoninvestedsomeofhisownmoneyinhisfloatplant.

11.Pilkington’sfirstfull-scaleplantwasaninstantcommercialsuccess.

12.TheprocessinventedbyPilkingtonhasnowbeenimproved.

13.Computersarebetterthanhumansatdetectingfaultsinglass.

THELITTLEICEAGE

AThisbookwillprovideadetailedexaminationoftheLittleIceAgeandotherclimaticshifts,but,beforeIembarkonthat,letmeprovideahistoricalcontext.Wetendtothinkofclimate-asopposedtoweather-assomethingunchanging,yethumanityhasbeenatthemercyofclimatechangeforitsentireexistence,withatleasteightglacialepisodesinthepast730,000years.OurancestorsadaptedtotheuniversalbutirregularglobalwarmingsincetheendofthelastgreatIceAge,around10,000yearsago,withdazzlingopportunism.Theydevelopedstrategiesforsurvivingharshdroughtcycles,decadesofheavyrainfallorunaccustomedcold;

adoptedagricultureandstock-raising,whichrevolutionisedhumanlife;

andfoundedtheworld’sfirstpre-industrialcivilisationsinEgypt,MesopotamiaandtheAmericas.Butthepriceofsuddenclimatechange,infamine,diseaseandsuffering,wasoftenhigh.

BTheLittleIceAgelastedfromroughly1300untilthemiddleofthenineteenthcentury.Onlytwocenturiesago,Europeexperiencedacycleofbitterlycoldwinters;

mountainglaciersintheSwissAlpswerethelowestinrecordedmemory,andpackicesurroundedIcelandformuchoftheyear.TheclimaticeventsoftheLittleIceAgedidmorethanhelpshapethemodernworld.Theyarethedeeplyimportantcontextforthecurrentunprecedentedglobalwarming.TheLittleIceAgewasfarfromadeepfreeze,however;

ratheranirregularseesawofrapidclimaticshifts,fewlastingmorethanaquarter-century,drivenbycomplexandstilllittleunderstoodinteractionsbetweentheatmosphereandtheocean.Theseesawbroughtcyclesofintenselycoldwintersandeasterlywinds,thenswitchedabruptlytoyearsofheavyspringandearlysummerrains,mildwinters,andfrequentAtlanticstorms,ortoperiodsofdroughts,lightnortheasterlywinds,andsummerheatwaves.

CReconstructingtheclimatechangesofthepastisextremelydifficult,becausesystematicweatherobservationsbeganonlyafewcenturiesago,inEuropeandNorthAmerica.RecordsfromIndiaandtropicalAfricaareevenmorerecent.Forthetimebeforerecordsbegan,wehaveonly‘proxyrecords’reconstructedlargelyfromtreeringsandicecores,supplementedbyafewincompletewrittenaccounts.Wenowhavehundredsoftree-ringrecordsfromthroughoutthenorthernhemisphere,andmanyfromsouthoftheequator,too,amplifiedwithagrowingbodyoftemperaturedatafromicecoresdrilledinAntarctica,Greenland,thePeruvianAndes,andotherlocations.Weareclosetoaknowledgeofannualsummerandwintertemperaturevariationsovermuchofthenorthernhemispheregoingback600years.

DThisbookisanarrativehistoryofclimaticshiftsduringthepasttencenturies,andsomeofthewaysinwhichpeopleinEuropeadaptedtothem.PartOnedescribestheMedievalWarmPeriod,roughly900to1200.Duringthesethreecenturies,NorsevoyagersfromNorthernEuropeexplorednorthernseas,settledGreenland,andvisitedNorthAmerica.Itwasnotatimeofuniformwarmth,forthen,asalwayssincetheGreatIceAge,therewereconstantshiftsinrainfallandtemperature.MeanEuropeantemperatureswereaboutthesameastoday,perhapsslightlycooler.

EItisknownthattheLittleIceAgecoolingbeganinGreenlandandtheArcticinabout1200.AstheArcticicepackspreadsouthward,NorsevoyagestothewestwerereroutedintotheopenAtlantic,thenendedaltogether.StorminessincreasedintheNorthAtlanticandNorthSea.Colder,muchwetterweatherdescendedonEuropebetween1315and1319,whenthousandsperishedinacontinent-widefamine.By1400,theweatherhadbecomedecidedlymoreunpredictableandstormier,withsuddenshiftsandlowertemperaturesthatculminatedinthecolddecadesofthelatesixteenthcentury.Fishwereavitalcommodityingrowingtownsandcities,wherefoodsupplieswereaconstantconcern.DriedcodandherringwerealreadythestaplesoftheEuropeanfishtrade,butchangesinwatertemperaturesforcedfishingfleetstoworkfurtheroffshore.TheBasques,Dutch,andEnglishdevelopedthefirstoffshorefishingboatsadaptedtoacolderandstormierAtlantic.AgradualagriculturalrevolutioninnorthernEuropestemmedfromconcernsoverfoodsuppliesatatimeofrisingpopulations.Therevolutioninvolvedintensivecommercialfarmingandthegrow