听力原文及答案4Word格式文档下载.docx

听力原文及答案4Word格式文档下载.docx

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Student:

It’saboutmytermpaperfortheurbanplanningclass.Insteadofjustdoinglibraryresearch,Iwasthinkingofdoingasurveyofmyownandusingthedatainthereport.

That’saniceidea.Ithinkdoingthiskindofhands-onprojectisgreatexperience,especiallyifyoudecidetogotograduateschool.

But,I’vebeenhavingalotofproblemsdesigningthesurvey.

Ahh…It’snotaseasyasitlooksisit?

No,nowI’mnotevensureifIshouldstickwithmyplanorswitchbacktoamoretraditionalpaper.

Well,youmightaswellgetsomeexperiencesoonerratherthanlater.What’syourtopicagain?

Nothingreallycomplex.IjustwantedtosurveylocalpeopleabouttheproposaltowidenRoute62fromatwolaneroadtoafourlanehighway.

Ok…

So,howdoIgoaboutselectingthepeopleIwanttosurvey?

AlotofwhatIreadhasstressedhavingarepresentativesample,butI’mnotsurehowtodoit.

Well,yesarepresentativesampleiscrucial.Youwantthepeopleyousurveytobeasclosetoanaccuratereflectionofthelargerpopulationyou’reinterestedinaspossible.Imaginethatthetownisacakewithraisinsinitandimaginethatforsomereasonmostoftheraisinsendupononesideofthecake.Ifyoucutapiecefromtheotherside,wouldthatbetrulyrepresentative?

Woulditbeanaccuratereflectionofthecake?

No,you’dbemissingtheraisins.

Exactly,soforyourprojectwhatifyouonlysurveyedpeoplewholivedinhousesalongRoute62?

Doyouthinkthatwouldbeuseful?

Well,nobecauseeveryonetherewouldprobablybeopposedtothewidening.

Yes,andthat’swhyarepresentativesampleisimportant.Youdon’twantasamplethat’sbiasedtoostronglyonewayortheother,sohowdoyoudothat?

Well,Icouldmakesuremysurveyreachespeopleinallpartsofthetown.

Good!

So,howcanyoudothat?

Well,Iwasgoingtomakephonecalls,justchoosenumbersatrandomfromthelocalphonedirectory.It’sbetterthanpassingoutquestionnairesbecausepeopleoftendon’tmailthemback,butIdon’tseehowIcangetarepresentativesampleusingthephone.

Well,makesureyou’regettinganicebalanceofnumbers.Thephonecompanycantellyouwhatnumbershavebeenassignedtodifferentpartsoftown;

forexample,phonenumbersinmyneighborhoodstartwith256andIliveontheedgeoftown…where,Iguessyou’regoingtofindalotof‘pro-highway’people,somakesureyoudon’tcallmostly256numbers.

Lecture1

Listentopartofalectureinanancienthistoryclass.

Alright,solikemanyancientcivilizations,theRomanshelpeddevelopimportanttechnologies.Todaywe’regoingtofocusononeparticulartechnologicaldevelopmentthatwasasartistic,aspleasingtotheeye,asitwasfunctional.I’mtalkingabouttheirwaterdistributionsystem,alsoknownasaqueducts.Aqueductsarechannelsthatleadwaterfromitssource,likeanundergroundspring,toanotherlocation,usuallyacity.Thisisimportantbecausewell,citiesneedlargewatersuppliesandtheRomanEmpirehadalotoflargecities.Rememberitwasoneofthelargestancientempires.Withouttheaqueducts,whichwerebigthroughouttheempire,welltheRomanEmpireprobablywouldn’thavespreadsofarorhadsuchhighlypopulatedcities.TakethecityofRome,thecapitaloftheRomanEmpire;

it’sestimatedthatithadbetween500,000andamillionresidents.Tosupportallthesepeoplewithwaterwasamajorengineeringachievement.Overaperiodofseveralhundredyears,elevenaqueductswerebuilttobringwatertoRomefromasfarawayas90kilometersandsomeestimatethattheydeliveredaboutathousandmetersofwaterperpersonperday.Well,thatamountofwaterwouldhavebeenimpossibletofindinRomeandtheareaimmediatelysurroundingit,plustheonlywatersourceinorclosetothecitywouldhavequicklybecomepolluted.Imeanwe’retalkingabouthalfamillionpeopleormore.Speakingofallthosepeople,aqueductsalsohelpedkeepancientRomeclean.Theconstantoverflowofwaterwouldflushthecity’strashout.

So,howwereaqueductsbuilt?

Well,firsttheyhadtofindafreshwatersource,usuallyanundergroundspring.Onceaspringwaslocatedandtestedforquality,engineerswouldfindthebestroute;

theroutewiththemostgradual,gentlegradient,orslope,downwardstowardsthecity.Thatmeansthesourcehadtobehigher,atahigherelevationthanthecityitwasservingsincethesystemofaqueductsreliedentirelyongravitytoleadthewaterdownthroughthepipesandchannels.TheRomanaqueductswerebuiltoutofpipes,generallyleadorearthenwarepipes,whichmadeupthebulkofanaqueduct.Tunnelsortrenchesweredugandthepipeswerelaidandcovered.Thiswaymostofanaqueductwashiddenandthelandabovecouldstillbeutilized.Alsotunnelswerelessvulnerabletoenemiesandsooneofthefirstaqueductswasbuiltentirelyunderground.Someofthesetunnels,specificallytheonesdeepunderthemountains,aresuchamazingengineeringachievements,it’sstillamysterytoushowancientRomanswentaboutsurveyingandbuildingthemandifthelandscapeinsomeareasdidn’tfitthespecificationsneededfortheaqueduct,ifsaytherewasasharpdip,ariverbed,orvalley,thenengineersbuiltanarcade.

AsyoucanseeaRomanarcadeisaseriesofarches.Anopenconcretechannelrunsalongthetopwhichkeptthewateratacertainleveleventhoughthelanddippeddownbecauseifyoulostthatlevelitwashardtogetitbackupagain.Thearcadesarewhatmanypeoplethinkofwhentheyhear‘Romanaqueducts’eventhoughthegreaterportionoftheaqueductssystemwasunderground,butthearcadesareabovegroundwhereeveryonecanseethemandthisiswheretheconjunctionofengineeringtechniquesandartisticcreationcomesin.

Thearcadeswerecertainlybeautiful.Infact‘rainbow’means…（Incomprehensible）…wellthey’rekindoflikelandscapeartbutthebeautycanmakeusforgetthepurposetheyserved,theirpracticaltechnologicalvalue.So,itwasn’tjustthepracticalaspectsofarcadesthatwereimportanttotheRomansandthearchedarcadeswereobviouslypractical,right?

Sayyouhadtobuildahighstructure.Buildingarchesrequireslessmaterialthanbuildingsolidwalls,right?

AndifyoucompareRomanaqueductsyou’llseetherefinedRomanskillsinbothstyleandscale.Arcades,especiallythosethatwerebuiltlater,areperfectexamplesofthemarriageoffunctionalityandelegance;

qualitiesthatwereveryimportanttoRomanarchitects;

qualitiesarchitectsstillstrivetoemulatetoday.

Lecture2

Listentopartofalectureinageologyclass.

Professor,Iwasalittleconfusedbyourreading.Imean,Iunderstoodit;

thestuffaboutradioactivedecay,butI’mnotsureabouthowitfitsin.

That’sunderstandable.Imeanttogiveyousomebackgroundinformationonradioactivedecaylastweek,butweranoutoftimeandIdidn’tgetachancetoexplainitsimportancetounderstandinggeology.So,togetanideaofwhywe’llbediscussingatopicthatmightseemmoreappropriatetoaphysicsclassthanageologyclass,let’squicklyreviewalittlehistory.Upuntilthe18thcentury,geologydidn’treallyexist,atleastnotasweknowittodayandthemostpopulartheoryabouttheageofEarthsuggestedtheworldwasjustseveralthousandyearsold,butthenJamesHuttoncamealong.

JamesHuttoncouldbeconsideredthefatherofmoderngeology.Heusedscientificobservations,notingphenomenalikeerosion,toformulateatheoryabouthowandwhenEarthwasformed.HuttoncorrectlyassertedthatEarth’ssurfacewasconstantlychangingandheattributedthatconstantchangetoafundamentalforce:

Earth’sinternalheat.ThatinternalheatwassupposedlyproducedbyanunendingseriesofchemicalreactionsinEarth’sinteriorandthereisoneotherimportantideaHuttonhad.Hebelievedthatgeologicalforcesthatareatworkinourtime,volcaniceruptions,orerosion,orwhatever,allthesethingswerealsohappeninginthepastatapproximatelythesamepacestheyarenow.Buildingonthatideaandonhisestimatesofhowlongitmusthavetakenformanyoftherockformationsweseetodaytohaveformed,HuttonhypothesizedthattheEarthwasmucholderthanpeoplehadpreviouslythought.

Excuseme,butyousaidEarth’sheatcamefromanunendingtheoryofchemicalreactionsinEarth’sinterior?

But,unendingmeansitgoesonforever,sortoflikeaperpetualmotionmachine.Ithoughtthat’snotpossible.

You’reright.Anunendingseriesofchemicalreactionswouldbelikeperpetualmotionandthelawsofphysicsareclearthere’snowaytokeeponproducingenergylikethatwithoutusingupwhatever’sfuelingthosereactions,sothesechemicalreactionscouldnotgoonforever.OnescientistwhostronglyemphasizedthispointwasWilliamThompson,betterknownasLordKelvin.

LordKelvin,herejectedtheideathatcontinualchemicalreactionsproducedEarth’sinternalheat.Instead,heassumedthatEarthhadstartedoutasmoltenrock,hotliquidrock,andhadbeencoolingeverysinceitwasinitsoriginalmoltenstate.Kelvinthencombinedthisassumptionwithsomesolidfacts.HeknewfromdescentsdownintosomeofthedeepminesinEuropethatEarth’stemperaturepredictablyincreaseswithdepth.It’shotteratthebottomofamineshaft.KelvinreasonedthatenergyfromEarth’shotinteriorwasbeinglost,drainedawayupatthesurfacea