托福听力TPO文本26

经典word整理文档，仅参考，双击此处可删除页眉页脚。本资料属于网络整理，如有侵权，请联系删除，谢谢！TPO26Conversation1NarratorListentoaconversationbetweenastudentandauniversityprintshopemployee.StudentHi.Isawyouradinthecampusnewspaper.EmployeeOh.Wedonthaveanyjobopeningrightnow.StudentOh,no.Imeanttheotherad,abouttheservicesyouprovideforstudents.Yousee,Ihavebeenworkingatthecampustutoringcenterasamathtutor.Butthingshavechanged,includingmyschedule.AndnowIwanttostartdoingtutoringworkindependently.Butinorderto,basically,startmyownbusiness,Ineedtogettheworkout.EmployeeOk.StudentIwasthinkingIshouldgetsomethingprintedupthatIcanhandouttopeople.EmployeeAh.Well,actually,Ijustprintedupsomegreat-lookingflyersforsomeonedoingthesamething.StudentFlyers.Yeah,thatsanidea.IguessthenIcouldpostthemaroundthecampus.EmployeeYeah.Andyoucanhandthemouttoo.But,oh,youknowwhat?Ididsomethingreallyneatforsomeonelastweek.Shedidntwanttogothetraditionalroute,youknow,businesscards,flyers,sowecustomizedpencilsforher.StudentPencils?EmployeeYeah.Youknow,alittlemessageprintedonthepencil.StudentOh,thatscool.1EmployeeYeah.Butyoushouldknow,itsnotourcheapestoption.Oh,andyouknowthoselittlestickynotes?StudentYoudothosetoo?EmployeeWell,wedidonce.Ithinkthosebrightpiecesofpaperwouldberealattentiongetters.Youknow,studentusethemallthetime,sotheyshouldbegoodforbusiness.Idontknowwhywetdonemore.StudentWow.EmployeeSovegotsomeoptions.StudentRight.Well,whataboutbusinesscards?Myfriendhasthesebusinesscards.Shedoestutoringtoo.Andshegotthematthisplaceintown,buttheywerekindofexpensive.EmployeeForbusinesscard?Well,Idontknowwhatyourfriendpaid.Butwecoulddosomethingrealsimpleanditwouldntbemuch.Likeforabatchof250foroneofourstandarddesigns,20dollarsmaybe.Student20dollarssoundsokay.EmployeeNow,therearesomeotherchoicesthatllaffectthecost.Youknow,likedifferentbackgroundpatters,usingcolorink,thatsortofthing.Anditalsodependsonhowmanywordsyouwanttoinclude.StudentOk.Well,IknowwhatIwantthemtosay.ButIamjustthinking,Ikindoflikethatpencilidea.EmployeeYeah.Ithoughtitwasneat.Now,ofcourseyoucanonlyfityournameandphonenumber,andlike,inyourcase,mathtutoringonit.StudentRight.Well,Icouldcustomdesignthebusinesscardsthrough,right?Thatswhatmyfriend2did.Shesaidshedesignedthematthecomputerrightthereattheprintshop.EmployeeWell,youcandothatheretoo.Butacustomdesignwouldbeabiggerinvestmentforyourbusinessthanoneofourstandarddesigns.StudentWell,Idontknow.Iaminterestedinbusinesscards,socanIlookatthestandarddesigns?1.Whydosethestudentgotospeaktotheman?A.TodiscussajobopportunityshehadheardaboutB.TolearnaboutoptionsforadvertidsingherbusinessC.ToseeifshecanchangeapreviousprintorderD.Todiscussadesignideathatshehasforbusinesscards2.Whydosethemanimplyaboutcustimizedstickynotes?A.Theyrequiremoretimetoproducethanotherprintproducts.B.Theyarelesseffectiveatattractingbusinessthanbusinesscards.C.Theyarenotususallyavaiableatotherprintshops.D.Theyshouldbeamorepopularchoiceofadvertisingthantheyare3.Whatdoesthemanimplyarethedisadvantgesofusingpencilstosdvertise?Clickon2answers.A.Theyareeasetolose.B.Theymightbemoredifficulttodistribute.C.Thereisnotmuchspaceforamessage.D.Theycostmorethanothermethods.4.Whatdidthestudentlearnfromherfriend'sexperience?A.Theprintshopintownprocessesordersquickly.B.Someprintshopsletcustomersdesigntheirownbusinesscards.C.Theuniveristyprintshophasspecialdiscountsforstudents.D.Distributingbusinesscardscansttractalotofattentiontoatutoringbusiness.5.Whatcanbeinferredaboutthestudnetswhenshesaysthis:A.Sheisconcernedaboutthecostofacustomdesign.B.Shethinksasimpledesignwouldattractmorecustomers.3C.Sheshouldliketoinvestmoremoneyinbusinesscards.D.Shewouldliketotakeadvantageofthediscountofferedbytheman.Lecture1-Advertising(GreenMarketing)NarratorListentopartofalectureinanadvertisingclass.ProfessorLastclasssomeoneaskedaboutgreenmarketing.Greenmarketingreferstocompaniespromotingtheproductsasenvironmentallyfriendly.Companiesoftenturntoadvertisingexpertstohelpthemdothis.Greenmarketingseemsrecent,butadvertisingprofessionalsgrewinterestinitseveraldecadesago.Theseedsforgreenmarketingwereprobablyplantedin1970,whenthefirstEarthDaytookplace.RalliesallovertheUnitedStateswereorganizedtoprotestenvironmentaldegradation.Some20milliondemonstratorsparticipatedinthatfirstEarthDay.Andithelpedsparkdozensofenvironmentallaws.ThebiggestwastheEndangeredSpeciesActof1973,whichprotectsimperiledanimalspeciesfromextinction.TherewasalsopassageoftheCleanWaterActandtheCleanAirActwasstrengthened.EarthDay,EnvironmentalLaws,EnvironmentalIssuesinthenews,BeingGreenwasenteringthemainstream.Andbusinessstartedsaying,hey,wecangetinvolvedinthis.Soin1975,amajoradvertisingtradegrouphelditsfirstworkshoponecologicalmarketing.Afewyearslater,webeganseeingadstappingintopeoplesenvironmentalconcerns.Butsomegreenmarketerslearnedthehardway,greenmarketingmuststillinvolveallthesameprinciplesofatraditionalmarketingcampaign.Youadmustattractattention,stimulateconsumers’interest,createadesireforyourproduct,andmotivatepeopletotakeactiontobuyyourproduct.Soletmetellyouaboutonegreenmarketingcampaignthatfailedatfirstandexplainwhy.Itwasacompactfluorescentlightbulb.Wellcallittheeco-light.Itwasfirstintroduced,Ibelieve,inthelate90s.Itcostfarmorethanaregularincandescentbulb.Theadvertisingmessagewas,basically,usethiseco-lightandsavetheplanet.Butthatmessagewasnteffective.Research4showsthatconsumersdontwanttoletgooffanytraditionalproductattributes,likeconvenience,priceandquality.Eventhoughsurveysindicatethatalmosteverybodycaresabouttheenvironment.Sothecompanyreintroducedtheeco-lightwithanewmessage,onethatemphasizedcostsavings,thattheeco-lightlowerselectricbillsandlastsforyears.Soitsgoodforearth,cost-effectiveandconvenientbecauseitdoesnthavetobechangedeveryfewmonths.Thisadcampaignworkedlikeacharm.Somethingelse,uh,thecompanythatmakestheco-light,researcherswouldconsideritanextremegreen’,notonlybecauseitsproductareenergy-efficient,butbecausethecompanytriestoreduceitsenvironmentalimpactinotherwaystoo．LikeinadditiontosellingEarth—friendlyproducts,itsofficesandfactoriesaredesignedtoconserveenergyanduseallsortsofrecycledmaterials．Acompanythatonlyrecyclesofficepaper,researcherswouldclassifyasa‘leangreenAndthereareotherdegreesofgreennessinbetween．Soifyourgreenmarketingstrategysgonnawork,yourmessageshouldbevalidonalldimensions．Whenacompanyasawholeiscreditedforreducingitsenvironmentalimpact,thiscanleadtobrandloyaltyPeoplewillcomebackandbuyyourproductmoreandmoreHowever,letssayyourefineforviolatingtheCleanWaterActwhilemanufacturingproductsfromrecycledmaterials.Thepublicwouldeventuallyfindout．Youtjustmaketheclaimthataproductisenvironmentallyfriendlyandnotfollowthrough．1.Whatisthelecturemainlyabout?A.ReasonsthatenvironmentallyfriendlyproductsoftencostmorethanotherproductsB.EvidencethatenvironmentallawshelpedincreasedemandforenvironmentallyfriendlyproductsC.DifferencesbetweengreenmarketingandtraditionalmarketingD.Thedevelopmentofatrendtomarketproductsasenvironmentallyfriendly2.Howdoestheprofessororganizethelecture?5A.Shegivessomehistoricalbackground,thenshepresentsacasestudy.B.Shedescribesseveralenvironmentallyfriendlyproducts,thensheexplainshowthepublicrespondedtothem.C.Shedescribesaproblem,thensheproposesseveralpossiblesolutions.D.Shedescribesanapproachtoadvertising,thensheexplainswhyitisoftenineffective.3.Accordingtotheprofessor,whydidthefirstefforttomarkettheEco-lightfail?A.TheadsdidnotexplainthattheEco-lightwasenvironmentallyfriendly.B.Theadsdidnotmentionthelong-termcostsavingthatresultfromusingtheEco-light.C.TheadsfortheEco-lightweretoolonganddetailed.D.TheprocessusedtomanufacturetheEco-lightdamagedtoenvrionment.4.Whatdoestheprofessorimplywhencompaniesthatare"extremegreen"and"leangreen"?A.Somecompanieshaveusedtheterm"extremegreen"and"leangreen"intheirads.B.Asystemisavailabletoclassifycompaniesaccordingtotheirenvironmentalprograms.C.Thereareimportantaspectsofgreenmarketingthathavebeenneglectedbyresearchers.D.Marketersneedtobecreativetokeeppeopleinterestedinenvironmentalissues.5.Whatopiniondoestheprofessorexpressaboutcompaniesthatusegreenadvertisingcampaigns?A.Thecompaniesshouldconsultenvironmentalistswhendevelopingthecampaigns.6B.Thecompaniesshouldpublicizeresearchthatsupportstheclaimsmadeintheiradvertisements.C.Thecompaniesshouldbefullycommittedtoprotectingtheenvironment.D.Thecompaniesshouldfindwaystolowerthepriceoftheirenvironmentallyfriendlyproducts.6.Whatdoestheprofessorimplywhenshesaysthis:A.Somegreenmarketingcampaignsaredifficulttoinplement.B.Somemarketingprinciplesneedtobeupdated.C.Thepointssheismakingisdifficulttoexplain.D.Somemarketershadunpleasantexperienceswithgreencampaigns.Lecture2-Biology(CarbonCycling)NarratorListentopartofalectureinabiologyclassProfessor．Justbeforetheendofthelastclass,westartedtalkingabouttracemetals,metalsfoundinlivingorganismsinverysmallquantitiesthatserveanimportantbiological,importantnutritivefunctioninthoseorganisms．Andonetracemetalthatservesanutritivefunctioniszinc．Zincassistsinanumberofprocessesinhumans,butwearegoingtofocusonjustone,onethatappliestoanumberoforganisms,notjusthumans．See,zincplaysamajorroleincarboncycling,theconversionofvariouskindsofmoleculeswithcarbon,Iikecarbondioxide,intootherkindsofmoleculeswithcarbonthatorganismscanSo,takerespirationOurbodies,ourcellsproducecarbondioxidewhentheybreakdownsugars．WeneedtogettheCO2outofourbodies,sotheCO2isconvertedintocarbonicacid,whichthebloodisabletocarrytothelungs．Oncethecarbonicacidreachesthelungs,sconvertedbackintocarbondioxidesothatwecanbreatheitout．Now,thiswholeconversionprocessreliesonaparticularenzyme．Uh,whorememberswhatanenzymeis?Bob?7StudentUh,itsaprotein,aspecifickindofprotein,onethatspeedsupchemicalreactions.ProfessorExactlyDifferentenzymesassistindifferentchemicalNow,theonethatspeedsuptheconversionofcarbondioxidehaszincinit．SothiszincenzymeiscriticalforgettingCO2outofourbodiesthroughthelungsAnditsalsoextremelyimportantforplantsBob,canyoutelluswhy?StudentFormakingfood,forphotosynthesis?Professor．Forphotosynthesis．Plantsalsoconvertcarbondioxideintodifferentformsofcarbon-containingmoleculesandtheconversionprocessusedreliesontheverysameenzymethatworksinhumans．Sozincisalsoimportantforplants．ButzincisscarceincertainenvironmentsAnditsparticularlyscarceinwatersnearthesurfaceofriversandlakesandshallowerpartsofoceans,whichmightmakeuswonderhowplantscouldlivethereatallInfact,therearealotofmarineplantsthatsurvive,thatgrowandreproduceinsurfacewaters．Inparticular,therearealotof．Diatomsaremicroscopic,photosyntheticorganismsandtheyareamajorsourceoffoodforotherorganismsintheThereareanumberofdifferenttypesofdiatoms,and,well,diatomsplayaveryimportantroleinthecarboncyclingprocess,becausetheyhelpmakecarbonavailabletootherorganismsindeeperpartsoftheocean．Thecarbonthatthesediatomsuseinphotosynthesisistransferredtootherpartsoftheoceanwhenthediatomsareeaten,say,byafishthatabsorbsthecarbonandthenswimstoanotherpartoftheocean,orwhendiatomsdieandfalltotheoceanfloor.Sohowdiddiatomssurviveifzincissoscarce?Well,recentlyresearchersdiscoveredthataspecifictypeofdiatommakesadifferentenzymethatservesthesamepurpose．Butthisenzymedoesntcontainzinc．Insteadthisnewenzymeincorporatesanothertracemetal,cadmium．Kelly,vegotaquestion?Student8Yeah．Ithoughtcadmiumwastoxic．Didntyousaythat?ProfessorItispoisonoustohumansUh.actually,weusedtothinkthatitwastoxictoallbiologicallife,thatitdidntserveanybiologicalpurpose．Butnewstudysuggeststhatcadmiumcanactuallysubstituteforzinc,thatorganismscanuseitinsteadofzincwhenthereisntenoughzincintheirenvironment．Now,thediscoveryofthiscadmium—basedenzymeisreallyimportantforanumberofreasonsItsactuallythefirstenzymewehavediscoveredthatusescadmiumSoitspossiblethatothernotsotypicaltracemetalsmaybeusedinchemicalprocesses,thatmarineorganismsmightmakeenzymesfromothertracemetalswhentheessentialoneisscarce．Andtheremaybeothertypesofdiatomsthatusecadmiumtocycle．ButssomethingelsetothinkaboutWhatisoneofthemostcommongreenhousegasesinouratmosphere,oneofthemajorculpritsinglobal．Carbondioxide,right?Now,ifallthesediatomsaretakingcarbondioxidefromthesurface,convertingitandtransportingittothebottomoftheocean,well,maybetheresmoretothatwholeprocess,thatcycle,somethingthatweveoverlooked．Sofurtherresearchmighttellusmoreaboutthesewarmingcycles．Conversation21.Whatisthelecturemainlyabout?A.ThediscoveryofapreviouslyunknowntracemetalB.TheroletracemetalsplayincarboncyclingC.WaysthatlivingorganismsridthemselvesoftracemetalsD.Waysthatzincinteractswithcarbondioxide2.Whatdoestheprofessorimplyabouttheconversationofcarbondioxidemoleculesinplants?A.Itisanunusuallycomplexchemicalprocess.B.Itonlytakesplaceinfullsunlight.9C.Itproceedsslowlywhencadmiumispresent.D.Itisregulatedbyanenzymethatmaycontainzinc.3.Accordingtotheprofessor,whyisitsurprisingthatmanymarineplantsareabletosurvivenearthesurfaceofoceans?A.Weatherconditionsnearthesurfacedisruptcertainlifeprocesses.B.Thesaltcontentofsurfacewatersisconstantlychanging.C.SurfacewaterscontainlowquantitiesofzincD.Surfacewatersabsorblargeamountsofcarbondioxide.4.Accordingtotheprofessor,whatimportantfunctiondodiatomsserve?A.Theyaltercadmiumsoitislesstoxictohumans.B.Theyhelpcyclezincinplaceswhereitisscarce.C.Theydistributecarbonthroughouttheocean.D.Theyremovecadiumfromtheoceanfloor.5.Whatpointdoestheprofessormakewhenshetalksaboutcadmiumbeingpoisonoustohumans?A.ThatcadmiumandzinccanserveasimilarfunctioninplantenzymesB.ThatbothcadmiumandzincarerareinplantenzymesC.ThatmosttracemetalsarepoisonoustohumansD.Thatcadmiumdoesnotserveanybiologicalpurpose6.Theprofessorstatesthatthediscoveryofanenzymecontainingcadmiumisimportant.Whataretworeasonsthatthisdiscoveryisimportant?Clickon2answers.A.Itmayleadtothediscoveryofnewenzymesthatuseothertracemetals.B.Itmayexplaintheocean'sincreasedlevelsofcarbondioxide.C.Itmayexplainthescarcityofsomeelementsintheocean.D.Itmayhelpscientistsbetterunderstandglobalwarming.10NarratorListentoaconversationbetweenastudentandherbiologyprofessor．ProfessorHi,Jean．Howwasthe…uh,theconference,right?theconferenceonvolunteerism?Thatswhereyouwerelastweek．StudentYeah.Itwasgreat.Imetalotofpeoplefromsomereallyamazingorganizationsthatareworkinginthearea．Nowitwouldbealoteasiertogetstudentstovolunteerinthecommunity．Plus,veneverbeentoanyofthebeachesherebefore．Beingatthebeachwasdefinitelyaplus．ProfessorWell,Ihopeyouhadtimetolookoverthenotesfromtheclassyoumissed．Youdidgetthenotes,right?StudentYup．IIlookthemoverbeforetomorrowsclass．ProfessorGood．Andletmeknowifyouhaveanyquestions.StudentWell,thereissomethingthatIwantedtoaskyounow．saboutsomethingInoticedatthe．ProfessorOh,sthat?StudentWell,see,therearealotofjellyfishthere,floatinginthewater.ProfessorThatcouldn’thavebeen.StudentNotforswimming.Butitwasinteresting.Imean,thejelleyfishwereglowing．Iswearthey．AndIamwonderingwhatthatsabout．ProfessorAh,glowingjellyfish．Thatisinteresting.Uh,itscalledbioluminescence．Andactuallywearegoingtotalkaboutitlaterinthesemester．Basically,bioluminescenceislighttsproduced11byachemicalreaction.StudentReally?Insidethejellyfish?ProfessorWell,notalljellyfish,abouthalfofthemActually,alotofmarineorganismshavethisability,especiallyindeeperpartsoftheocean．StudentOh?Igetit.Likethedarkeritgets,themorethefishneedslight,right?ProfessorWell．bioluminescenceservesanumberoffunctions．Mostaquaticorganismsuseitforcommunicationandforattractingprey．Butjellyfishusuallyuseitasadefenseagainstpredators．Somejellyfishproducebrightflashesoflightthatconfusepredators,to,uh,tostartlethem．Butjellyfishclosertothesurface,probablylikethejellyfishyousaw,theyusebioluminescencetohide．Thelighttheyproducematchesthecolorofthedimsunlight,sotheyblendin,and,uh,andpredatorstseethem．StudentWow,really?Well,Iamlookingforatopicformytermpaper,somaybeIcoulddoitontheseglowingjellyfish．ThatswhyIwantedtoaskyouaboutthem,youknow,tofindoutiftherewasreallysomethingtowriteabout．ProfessorItsagreattopicButyou’IIhavetomakesurethetopicisLikeIsaid,abouthalfofalljellyfisharebioluminescent,soyoumaywanttolookataparticulartypeofjellyfishorseveraltypesthatbenefitfrombioluminescenceinthesameway,oryoucouldinvestigatecurrentresearchonbioluminescence,on,onthechemicalprocess,or…Heresanidea．Youseemtobeveryinvolvedinlocalissues．Seeifyoucanidentifythejellyfishyouobservedonthebeachandhowtheyfitintothelocalecosystem．StudentYeah,youknow,someoftheenvironmentalgroupsImetlastweekmightevenbeabletohelp．1.Whydoesthestudentgotoseetheprofessor?12A.ToobtainnotesfromaclassshemissedB.TodiscussaconfererncesheattendedC.ToaskaboutapossibletopicforaresearchpaperD.Toclarifyinformationaboutvolunteeringinthecommunity2.Whatdoesthestudentsayabouttheconferencesheattended?A.Itwillhelpconvincestudentstogetinvolvedinthecommunity.B.Ittaughtheralotaboutmarineecosystems.C.Ithelpedhergainavolunteerpositionatalocalorganization.D.Fewstudentswereinvolvedintheconference.3.Whatcausedthewomantobecomeinterestedinbioluminescence?A.Itwasmentionedinthenotesfromaclassshemissed.B.Sheobservedthephenomenonwhileonarecenttriptoaconference.C.Avolunteersheworkedwithtoldheraboutseeingsomebioluminescentfish.D.Sheheardatalkaboutbioluminescenceatconferencesheattended.4.Accordingtotheprofessor,whywerethejellyfishthatthestudentsawglowing?A.Theywereavoidingpredatorsbyblendinginwiththeirsurroundings.B.Theyweretryingtoconfusepredatorswithbrightflashesoflight.C.Theywerecommunicationwitheachother.D.Theyweretryingtolightupthedarkwatersotheycouldseeprey.5.Whatdoestheprofessorimplyaboutthestudent'sproposedresearchtopic?A.Avarietyofbioluminescentorganismsshouldbeincludedintheresearch.B.Writingaboutthetopicmightbedifficultbecasuethereissomuchinformationonit.C.Thestudentshouldchooseatopicthathasalreadybeencoveredinclass.D.ThestudentshouldexplainhowbioluminescencebenefitsvariousspeciesofjellyfishDifferently.13Astronomy(Comets)NarratorListentopartofalectureinanastronomyclass.Professor0KWehavebeenlookingatsomeofthesmallermembersofoursolarsystem,Youalreadyknowaboutthestructureofcomets．Letscontinueourdiscussionnowbytalkingaboutorbits,especiallythoseoftheso-calledperiodic-orbitcomets．ThesearethecometsthatcirclearoundtheSunprettyregularly．Theyreturnagainandagain,predictably,afteracertainperiodoftimeThatswhywesaytheirorbitsareperiodicProbablythemostfamousandbrightestoftheseisscomet．Halleyscometcomesfromfaroutinthesolarsystem,goesinclosetotheSun,andthenoutagainAtitsclosestapproachtotheSun,HalleyscometisabouttwiceasclosetotheSunasEarthisAndatitsfarthestIt'saboutthirty-fivetimesfartherfromtheSunthanweare,whichputsitoutbeyondNeptune.Basically,theideahereisthataperiodiccomet,withitsveryelongatedorbit,justkeepscomingbackaroundagainandagain．WithHalleyscomet,well,itreturnsevery75years,．ButwhereisHalleyscometduringmostofthistime?Well,likeallorbitingbodies,acometmovesfasterwhenitsclosertotheSun．Soitonlyspendsaboutayearortwoinourneighborhood,insidetheorbitofJupiter．MostofitstimeisspentwayoutbeyondJupitersorbit,pokingalongnearthefartherreachesofitownorbitBecauseofthis,wecanonlyseesforafewmonthsevery75years,firstonitswayintowardtheSun,andthenonitswayoutagain．Now,yourememberfromourpreviousdiscussionthatacometsnucleus,itscore,ismadeupoficeanddust,likeafrozensnowballAndasitapproachestheSun,itstartstoheatAndsomeoftheicevaporizesintogasandspreadsoutfromthenucleus．Thegasesthatvaporizefromthecomet,thecometnevercollectsthembackagain,sooneveryorbit,thecometleavespartofitselfbehind．Howoldisthissolarsystem?Fourandahalfbillionyearsremember?AndHalleysis14goingaroundtheSunonceevery75yearsandlosingstuffeachSothecometshouldbelonggonebynow,right?Imean,howcomeHalleysisstillthere?Afterfourandahalfbillion．Howcoulditbe?Well,theansweristhatthiscomethasntalwaysbeeninsuchashortperiodicorbit,sinceonceacometgetsintoanorbitthatkeepsitcominginclosetotheSunquitefrequentlyWell,thatcometsprobablynotgoingtobearoundtoomuchlonger.SothiskindofperiodicorbitisonlyaphaseinacometslifeAphasethatjustprecedesitsfinalWe’veseencometsdothat,goingtowardtheSunandthencomebackaround,tornintopieces．Butlotsofcometsarentlikethat．Theycomein,passbehindtheSun,andthentravelbackout．Butwithanorbitsolarge,anditsfarthestplacesofarawayfromtheSunthatwejustdontknowhowfaroutitgoesWejustcantdeterminethatveryaccuratelyfromtheclose-inpartoftheorbitthatwedoSotheseareoftencalledparabolic-orbitcometsParabolicmeanstheorbitisopenatthefarend．ActuallytheorbitprobablydoescloseandreturnthecomettothevicinityoftheSuneventually,buttheperiodmightbetensofthousandsofyears．Andbasically,wecantdetermine．Sowejust,werefertothemasopen-endedparabolic-orbitcomets．So,whatcanchangeacometwithoneoftheselongorbitswheretheyonlycomebytheSunoccasionallyintoamuchmorefrequentperiodicvisitor?Well,gravitationalinteractionwithplanets,right?lfacometononeoftheselongperiodorbitsatsomepointcomesclosetoJupiterorSaturnoroneoftheotherplanets,thenthepullofthatplanetsgravitymightaltertheorbit,maybemakeitmuchshorter．Sothiscomet,ifithappenstopassbyaplanetjusttherightway,itcanbedrawnintoaneworbit,onethatllcaptureitandkeepitcomingbackaroundtheSunmuchmoreoften．1.Whatisthelecturemainlyabout?A.TheorbitsofcometsB.UniquecharacteristicsofafamouscometC.ThestructureofcometsD.Theoriginandlifecycleofcomets2.Accordingtotheprofessor,whathappensasacometapproachestheSun?Clickon2answers.15A.Itsnucleuslosessomematerial.B.Itscorebecomesbrighter.C.Itmovesfaster.D.ItabsorbsgasesfromtheSun.3.WhydoestheprofessoremphasizetheamountoftimethatHailey'sCometisbeyondtheorbitofJupiter?A.Toaccountforthecomet'ssompositionoficeanddustB.ToshowtheeffectofJupiter'sgravityonthecomet'sorbitC.Toarguethatthecomet'sorbitshouldnotbeconsideredperiodicD.ToexplainwhythecometisnotvisiblefromEarthveryoften4.WhatdoestheprofessorimplyabouthistoryofHailey'sComet?A.Hailey'sCometdidnotalwayshavethesameorbitithasnow.B.Hailey'sCometusedtobemuchsmallerthanitisnow.C.Hailey'sComethasalwayshadthesameorbitthatithasnow.D.Hailey'sCometismuchyoungerthantherestofthesolarsystem.5.Whatistheprofessor'sopinionaboutthename"parabolic-orbitcomets"?A.Itisnotwidelyacceptedamongastronomers.B.Itisprobablynotstrictlyaccurate.C.Itisnotatermthatthestudentsneedtolearn.D.Itwillprobablybereplacedsoonwithanewname.6.Accordingtotheprofessor,whatcanchangeaparabolic-orbitcometintoaperiodic-orbitcomet?A.Thelossofsomeofthecomet'smaterialB.TheforceofescapinggasesC.ThegravitationalinfluenceofaplanetD.EnergyfromtheSun16Lecture4-ArtConservation(ArchimedesPalimpsest)NarratorListentopartofalectureinanartconservationclass.ProfessorSofarwehavebeentalkingallsemesteraboutrestoringandpreservingpiecesofart，likeancientearlyoilpaintingsetcButalthoughourfieldiscalledartconservationitalsoinvolves…what?StudentUmpreservingothertypesofculturalmaterialstooProfessorVerygoodNotjustartOldartifactsareveryvaluablewhentheyrepresentearlytechnologies,allcontainimportanthistoricalinformation．Infact，letmegiveyouanexample．YouveheardabouttheGreekscholarwholivedmorethan000yearsIamArchimedeswasagreatmathematician．Forexample，hediscoveredtheformulaforthevolumeofaNotmuchofhisworkhasSurvivedbutwhathasSurvivedisbrilliantAndthenin1906，aPalimpsestof’writingwasdiscovered．Now,apalimpsestisatypeofmanuscriptthatcontainswritingshiddenbecausesomethingelsewaswrittenoveritlater．llexplaininaminute．ThisArchimedes