雅思真题原文.docx

雅思真题原文.docx

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雅思真题原文

Materialsforlecture16-18

Readingpassage1

Questions1-13arebasedonthefollowingpassage.

Sheetglassmanufacture:

thefloatprocess

Glass,whichhasbeenmadesincethetimeoftheMesopotamiansandEgyptians,islittlemore

thanamixtureofsand,sodaashandlime.Whenheatedtoabout1500degreesCelsius（C）this

becomesamoltenmassthathardenswhenslowlycooled.Thefirstsuccessfulmethodformaking

clear,flatglassinvolvedspinning.Thismethodwasveryeffectiveastheglasshadnottouched

anysurfacesbetweenbeingsoftandbecominghard,soitstayedperfectlyunblemished,witha

‘firefinish’.However,theprocesstookalongtimeandwaslabourintensive.

°

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

ThefloatprocessformakingflatglasswasinventedbyAlistairPilkington.Thisprocessallowsthe

manufactureofclear,tintedandcoatedglassforbuildings,andclearandtintedglassforvehicles.

Pilkingtonhadbeenexperimentingwithimprovingthemeltingprocess,andin1952hehadthe

ideaofusingabedofmoltenmetaltoformtheflatglass,eliminatingaltogethertheneedfor

rollerswithinthefloatbath.Themetalhadtomeltatatemperaturelessthanthehardening

pointofglass（about600C）,but°couldnotboilatatemperaturebelowthetemperatureofthe

moltenglass（about1500C）.The°bestmetalforthejobwastin.

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

60percentoftheflatglassmarketatthattimewasforsix-millimetreglass.

Pilkingtonbuiltapilotplantin195.3andby1955hehadconvincedhiscompanytobuildafull-scaleplant.However,ittook14monthsofnon-stopproduction,costingthecompany

￡100,000amonth,beforetheplantproducedanyusableglass.Furthermore,oncethey

succeededinmakingmarketableflatglass,themachinewasturnedoffforaservicetoprepareitforyearsofcontinuousproduction.Whenitstartedupagainittookanotherfourmonthstogettheprocessrightagain.Theyfinallysucceededin1959andtherearenowfloatplantsallovertheworld,witheachabletoproducearound1000tonsofglasseveryday,non-stopforaround15

years.

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

Theprincipleoffloatglassisunchangedsincethe1950s.However,theproducthaschangeddramatically,fromasinglethicknessof6.8mmtoarangefromsub-millimetreto25mm,fromaribbonfrequentlymarredbyinclusionsandbubblestoalmostopticalperfection.Toensurethehighestquality,inspectiontakesplaceateverystage.Occasionally,abubbleisnotremovedduringrefining,asandgrainrefusestomelt,atremorinthetinputsripplesintotheglassribbon.Automatedon-lineinspectiondoestwothings.Firstly,itrevealsprocessfaultsupstreamthatcanbecorrected.Inspectiontechnologyallowsmorethan100millionmeasurementsasecondtobemadeacrosstheribbon,locatingflawstheunaidedeyewouldbeunabletosee.Secondly,itenablescomputersdownstreamtosteercuttersaroundflaws.

Floatglassissoldbythesquaremetre,andatthefinalstagecomputerstranslatecustomerrequirementsintopatternsofcutsdesignedtominimisewaste.

Questions9-13

DothefollowingstatementsagreewiththeinformationgiveninReadingPassage1?

Inboxes9-13onyouranswersheet,write

TRUE

FALSE

NOTGIVEN

ifthestatementagreeswiththeinformation

ifthestatementcontradictstheinformation

ifthereisnoinformationonthisinthepassage

9.Themetalusedinthefloatprocesshadtohavespecificproperties.

10.Pilkingtoninvestedsomeofhisownmoneyinhisfloatplant.

11.Pilkington’sfirst-scalefullplantwasaninstantcommercialsuccess.

12.TheprocessinventedbyPilkingtonhasnowbeenimproved.

13.Computersarebetterthanhumansatdetectingfaultsinglass.

THELITTLEICEAGE

AThisbookwillprovideadetailedexaminationoftheLittleIceAgeandotherclimaticshifts,but,beforeIembarkonthat,letmeprovideahistoricalcontext.Wetendtothinkofclimate

-asopposedtoweather-assomethingunchanging,yethumanityhasbeenatthemercyofclimatechangeforitsentireexistence,withatleasteightglacialepisodesinthepast730,000years.OurancestorsadaptedtotheuniversalbutirregularglobalwarmingsincetheendofthelastgreatIceAge,around10,000yearsago,withdazzlingopportunism.They

developedstrategiesforsurvivingharshdroughtcycles,decadesofheavyrainfallorunaccustomedcold;adoptedagricultureandstock-raising,whichrevolutionisedhumanlife;andfoundedtheworld’firstpre-industrialcivilisationsinEgypt,MesopotamiaandtheAmericas.Butthepriceofsuddenclimatechange,infamine,diseaseandsuffering,wasoftenhigh.

BTheLittleIceAgelastedfromroughly1300untilthemiddleofthenineteenthcentury.Onlytwocenturiesago,Europeexperiencedacycleofbitterlycoldwinters;mountainglaciersintheSwissAlpswerethelowestinrecordedmemory,andpackicesurroundedIcelandformuchoftheyear.TheclimaticeventsoftheLittleIceAgedidmorethanhelpshapethe

modernworld.Theyarethedeeplyimportantcontextforthecurrentunprecedentedglobalwarming.TheLittleIceAgewasfarfromadeepfreeze,however;ratheranirregularseesawofrapidclimaticshifts,fewlastingmorethanaquarter-century,drivenbycomplexandstilllittleunderstoodinteractionsbetweentheatmosphereandtheocean.Theseesawbroughtcyclesofintenselycoldwintersandeasterlywinds,thenswitchedabruptlytoyearsofheavyspringandearlysummerrains,mildwinters,andfrequentAtlanticstorms,ortoperiodsofdroughts,lightnortheasterlywinds,andsummerheatwaves.

CReconstructingtheclimatechangesofthepastisextremelydifficult,becausesystematicweatherobservationsbeganonlyafewcenturiesago,inEuropeandNorthAmerica.Records

fromIndiaandtropicalAfricaareevenmorerecent.Forthetimebeforerecordsbegan,we

haveonly‘proxyrecords’reconstructedlargelyfromtreeringsandicecores,supplementedbyafewincompletewrittenaccounts.Wenowhavehundredsoftree-ringrecordsfromthroughoutthenorthernhemisphere,andmanyfromsouthoftheequator,too,amplified

withagrowingbodyoftemperaturedatafromicecoresdrilledinAntarctica,Greenland,thePeruvianAndes,andotherlocations.Weareclosetoaknowledgeofannualsummerandwintertemperaturevariationsovermuchofthenorthernhemispheregoingback600years.

DThisbookisanarrativehistoryofclimaticshiftsduringthepasttencenturies,andsomeof

thewaysinwhichpeopleinEuropeadaptedtothem.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.Therevolutioninvolvedintensivecomme