可以粘贴复制的word版本-剑桥雅思真题-8-test2

READINGREADINGPASSAGE1Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReadingPassage1below.Sheetglassmanufacture:thefloatprocessGlass,whichhasbeenmadesincethetimeoftheMesopotamiansandEgyptians,islittlemorethanamixtureofsand,sodaashandlime.Whenheatedtoabout1500degreesCelsius(°C)thisbecomesamoltenmassthathardenswhenslowlycooled.Thefirstsuccessfulmethodformakingclearflatglassinvolvedspinning.Thismethodwasveryeffectiveastheglasshadnottouchedanysurfacesbetweenbeingsoftandbecominghard,soitstayedperfectlyunblemished,witha'firefinish'.However,theprocesstookalong-timeandwaslabourintensive.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.Pilkingtonbuiltapilotplantin1953andby1955hehadconvincedhiscompanytobuildafull-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,fromasinglethicknessof6.8mmtoarangefromsub-millimetreto25mm,fromaribbonfrequentlymarredbyinclusionsandbubblestoalmostopticalperfection.Toensurethehighestquality,inspectiontakesplaceateverystage.Occasionally,abubbleisnotremovedduringrefining,asandgrainrefusestomelt,atremorinthetinputsripplesintotheglassribbon.Automatedon-lineinspectiondoestwothings.Firstly,itrevealsprocessfaultsupstreamthatcanbecorrected.Inspectiontechnologyallowsmorethan100millionmeasurementsasecondtobemadeacrosstheribbon,locatingflawstheunaidedeyewouldbeunabletosee.Secondly,itenablescomputersdownstreamtosteercuttersaroundflaws.Floatglassissoldbythesquaremetre,andatthefinalstagecomputerstranslatecustomerrequirementsintopatternsofcutsdesignedtominimisewaste.Questions1-8Completethetableanddiagrambelow.ChooseNOMORETHANTWOWORDSfromthepassageforeachanswer.Writeyouranswersinboxes1-8onyouranswersheet.EarlymethodsofproducingflatglassMethodAdvantages......V'■■■n'--■:■:■■:■.'■■■■'Disadvantages1.......................•Glassremained2...................•Slow•3.......................Ribbon•Couldproduceglasssheetsofvarying4.......................•Non-stopprocess•Glasswas5.......................•20%ofglassrubbedaway•MachineswereexpensivePilkington'sfloatprocessQuestions9-13DothefollowingstatementsagreewiththeinformationgiveninReadingPassage1?Inboxes9-13onyouranswersheet,writeTRUEifthestatementagreeswiththeinformationFALSEifthestatementcontradictstheinformationNOTGIVENifthereisnoinformationonthis9Themetalusedinthefloatprocesshadtohavespecificproperties.10Pilkingtoninvestedsomeofhisownmoneyinhisfloatplant.11Pilkington'sfirstfull-scaleplantwasaninstantcommercialsuccess.12TheprocessinventedbyPilkingtonhasnowbeenimproved.13Computersar