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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