老托30篇听力稿Word格式.docx
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老托30篇听力稿Word格式.docx
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sdefensesystembycuttingthemainveinthatdeliversthepoisontotheleaves.Thisveincuttingisjustonemethodthebeetlesusedtoprepareasafemeal.Anotherisbycuttingapathallthewayacrosstheleavestoholdtheflowofchemicals.Thentheysimplyeatbetweentheveinsofpoison.Inthepast,scientistswhostudiedinsectadaptationtoplantdefenseshavefocusedonchemicalresponses.Thatis,howtheinsectscanneutralizeoralterthepoisonoussubstancesplantsproduce.What'
suniqueaboutthischewingstrategyisthatthebeetleisactuallyexhibitingabehavioralresponsetotheplant'
sdefensesratherthanthemorecommonchemicalresponse.Itisonlyafterabeetle'
ssurvivedseveralencounterswiththeplant'
sresinthatitlearnshowtoavoidthepoison:
bychewingthroughtheresintransportingveinsonthenextleafiteats.Andthusgivesitselfasafemeal.However,itcantakeabeetleanhourandahalfofcarefulveincuttingtoprepareasmallleafthattakesitonlyafewminutestoeat.So,thoughthemethodiseffective,it'
snotveryefficient.
NO2:
Humanpopulationsneartheequatorhaveevolveddarkskinovermanygenerationsbecauseofexposuretothefiercestraysofthesun.Asimilarphenomenonhasalsooccurredinotherpartsoftheanimalkingdom.TheAfricangrassmouseisagoodexample.Mostmicearenocturnal,buttheAfricangrassmouseisactiveduringdaylighthours.Thismeansthatitspendsitsdayssearchingforfoodinthesemi-drybushinscrubbyhabitatsofeasternandsouthernAfrica.Itsfurrystripe'
slikeachipmunk'
s,whichhelpsitblendinwithitsenvironment.Becauseitspendsalotoftimeintheintensetropicalsun,thegrassmousehasalsoevolvedtwoseparatesafeguardsagainstthesun'
sultravioletradiation.First,likethepopulationofhumansinthisregionoftheworld,theskinofthegrassmousecontainslotsofmelanin,ordarkpigment.Secondandquiteunusual,thismousehasalayerofmelanin-pigmentedtissuebetweenitsskullandskin.ThisuniquecapprovidesanextrameasureofprotectionforthegrassmouseandthreeothertypesofAfricanmouse,likerodentsthatareactiveduringtheday.Theonlyotherspeciesscientistshasidentifiedwiththesamesortofskulladaptationisthewhitetent-makingbatoftheCentralAmericantropics.Althoughthesebatssleepduringtheday,theydosocurledupwiththeirheadsexposedtothesun.
NO3:
We'
vebeenlookingatfearfromabiologicalperspective,andsomeoneaskedwhetherthetendencytobefearfulisgenetic.Whatsomestudiesdonewithmiceindicatethatmammalsdoinheritfearfulnesstosomedegree.Inonestudy,forinstance,agroupofmicewasplacedinabrightlylitopenboxwithnohidingplace.Someofthemicewanderedaroundtheboxanddidn'
tappeartobebotheredaboutbeingsoexposed.Butothermicedidn'
tmove.Theystayedupagainstonewallwhichindicatedthattheywereafraid.Well,whenfearfulmice,oryoumightsayanxiousmiceliketheoneswhostayedinoneplace,whenmicelikethesewerebredwithoneanotherrepeatedly,afterabouttwelveorsogenerations,thenalloftheoffspringshowedsimilarsignsoffearfulness.Andevenwhenanewbornmousefromthisgenerationwasraisedbyamotherandwithothermicewhowerenotfearful,thatmousestilltendedtobefearfulasanadult.Nowwhyisthis?
Wellit'
sthoughtthatspecificgenesinananimal'
sbodyhaveaninfluenceonanxiousbehavior.Thesearegenesthatareassociatedwithparticularnerve-cellreceptorsinthebrain.Andthedegreeofoveralloffearfulnessinthemammalseemstodependinlargepartonthepresenceorabsenceofthesenerve-cellreceptors.Andthisappearstoapplytohumansaswellbytheway.Butwhileatendencytowardsanxietyandfearmaywellbeaninheritedtrait,thespecificformthatthefeartakeshasmoretodowiththeindividual'
senvironment.Soaparticularfear,likeafearofsnakesorthefearofspider,say,isnotgenetic,buttheoveralltendencytohavefearfulresponses,is.
NO4:
Let'
sturnourfocusnowtoadvertising.Weallknowwhatanadvertisementis:
It'
sessentiallyamessagethatannouncessomethingforsale.Nowthere'
sanimportantpreconditionthatmustexistbeforeyouhaveadvertising,andthat'
salargesupplyofconsumergoods,thatis,thingstosell.Youseeinaplacewherethedemandforaproductisgreaterthanthesupply,thereisnoneedtoadvertise.Nowtheearliestformsofadvertisinggoingbackmanyhundredsofyearswithasimplesignovershopdoorsthattoldyouwhethertheshopwasabakery,abutchershoporwhathaveyou.Thenwiththeadventofprinting,advertisingincreasedsubstantially.Asforproductslikecoffee,teaandchocolateappearedinnewspapersandotherperiodicals,aswellasonthesidesofbuilding.IntheAmericancolonies,advertisingandcommunicationmedialikenewspapersandpamphletsbecameamajorfactorinmarketinggoodsandservices.Bymodernstandards,theseearlyadvertisementswerequitesmallandsubdued,notassplashy,wholepagespreadoftoday.StillsomeofthemappearedonthefrontpagesofnewspapersprobablybecausethenewsoftenconsistedoflessrefreshreportsfromdistantEuropewhilethenewswerecurrentandlocal.Advertisingreallycameanddoitsoandbecameanessentialpartofdoingbusinessduringtheindustrialrevolution.Suddenlytherewasamuchgreatersupplyofthingstosell.Andaswesaidearlier,thatisthedrivingforcebehindadvertising.People'
sattentionhadtobedrawntothenewproduct.Let'
stakealookatsomeoftheadvertisementsfromthattime.
NO5:
Movingawayfromnewspapers,let'
snowfocusonmagazines.Now,thefirstmagazinewasalittleperiodicalcalledTheReview,anditwasstartedinLondonin1704.Itlookedalotlikethenewspapersofthetime.Butintermsofitscontent,itwasmuchdifferent.Newspaperswereconcernedmainlywithnewsevents,butTheReviewfocusedonimportantdomesticissuesofthedayaswellasthepoliciesofthegovernment.NowinEnglandatthetime,peoplecouldstillbethrowninjailforpublishingarticlesthatwerecriticaloftheking.Andthat'
swhathappenedtoDanielDefoe.HewastheoutspokenfounderofTheReview.DefoeactuallywrotethefirstissueofTheReviewfromprison.Yousee,hehadbeenarrestedbecauseofhiswritingsthatcriticizedthepoliciesoftheChurchofEngland,whichwasheadedbytheking.Afterhisrelease,DefoecontinuedtoproduceTheReviewandmagazinestartedtoappearonamorefrequentschedule,aboutthreetimesaweek,itdidn'
ttakelongforothermagazinestostartpoppingup.In1709,amagazinecalledTheTatlerbeganpublication.Thisnewmagazinecontainedamixtureofnews,poetry,politicalanalysis,andphilosophicalessays.
NO6:
ThecattleranchingindustrystartedinthenewwesternUnitedStatesinthelate1800s.Astheindustrydeveloped,sodidthehorseridingconteststhatwecalledrodeos.Rodeosweren'
talwaysthebigentertainmentshowsthatweseenowadays.Thefirstonesweresmallcontestsstartedasaformofcompetitionamongpeoplehistoricallyreferredtoascowboys,althoughtheydidincludebothmenandwomen.Onedutyofthecowboyswastoguideherdsofcattlefromthegrassyrangesintotownsaroundtherailroadlineswherethecowswereloadedontotrains.Thecowboyswouldgathernearthesecowtownstocompetefortheunofficialtitle:
besthorserider.Theywoulddemonstratetheridingskillstheyhadlearnedasamatterofsurvival.Theaudiencewascomposedmainlyofothercowboyswhowatchedthecompetitorscriticallysincetheyknewwhattheeventswereallabout.Rodeoconteststookadifferentturninthe1890swhenorganizersbegantoholdcowboysportsduringyearlyagriculturalfairs.Whatwasdifferentwastheaudience.Itconsistedmostlyofpeoplewhowereunfamiliarwithlifeontherange.Theywereamazedbytheskilloftheridersandtheintelligenceofthehorses.Rodeoatagriculturalfairsbecamesopopularthatranchersandbusinesspeoplebegantoorganizerodeosasindependentevents,separatefromfairs.Theorganizersbuiltlargearenasandearnedmoneybyrequiringspectatorstopayforadmission.OneofthemostnotablerodeosofthistypeisstillheldannuallyinWyoming.It'
scalledFrontierDays.WhileFrontierDaysisnotthefirstindependentrodeo,itistheannualshow,takingplaceeachyearsince1897.
NO7:
Lastweek,yourecall,wediscussedtheearlydevelopmentofrailroadsintheUnitedStates.TodayIwanttomentionanevenearlierformoftransportation,onethatbroughtthefirstEuropeansettlerstoAmerica.Andthat'
sthewoodensailingship.Fromcolonialtimes,sailingshipswerevitaltotheeconomy.Manycoastaltownsdependedonfishingorwhalingforemploymentandincome.Thiswasespeciallytrueinthenortheasternstates.Andtherethewoodfromnearbyforestsandtheskillsoflocaldesignersandworkersalsoformedthebasisofanimportantshipbuildingindustry.Butthebigprofitsweretobemadeontradewithfarawayplaces.Andsinceseacaptainsoftenbecamepartofownersoftheirships,theyhadastronginterestinthecommercialsuccessoftheirvoyages.SotheseYankees,that'
swhatUSsailorsandofficerscametobecalled,theycarriedonaveryprofitabletradewithotherpartsoftheworld.Thehighpointofthistradeca
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