乱七八糟高频阅读机

1.乙醇汽油19931.乙醇汽油199304Although,recentyearshaveseensubstantialreductionsinnoxiouspollutantsfromindividualmotorvehicles,thenumberofsuchvehicleshasbeensteadilyincreasing,consequently,morethan100citiesintheUnitedStatesstillhavelevelsofcarbonmonoxide,particulatematter,andozone(generatedbyphotochemicalreactionswithhydrocarbonsfromvehicleexhaust)thatexceedlegallyestablishedlimits.Thereisagrowingrealizationthattheonlyeffectivewaytoachievefurtherreductionsinvehicleemissions—shortofamassiveshiftawayfromtheprivateautomobile—istoreplaceconventionaldieselfuelandgasolinewithcleaner-burningfuelssuchascompressednaturalgas,liquefiedpetroleumgas,ethanol,ormethanol.Allofthesealternativesarecarbon-basedfuelswhosemoleculesaresmallerandsimplerthanthoseofgasoline.Thesemoleculesburnmorecleanlythangasoline,inpartbecausetheyhavefewer,ifand,carbon-carbonbonds,andthehydrocarbonstheydoemitarelesslikelytogenerateozone.Thecombustionoflargermolecules,whichhavemultiplecarbon-carbonbonds,involvesamorecomplexseriesofreactions.Thesereactionsincreasetheprobabilityofincompletecombustionandaremorelikelytoreleaseuncombustedandphotochemicallyactivehydrocarboncompoundsintotheatmosphere.Ontheotherhand,alternativefuelsdohavedrawbacks.Compressednaturalgaswouldrequirethatvehicleshaveasetofheavyfueltanks—aseriousliabilityintermsofperformanceandfuelefficiency—andliquefiedpetroleumgasfacesfundamentallimitsonsupply.Ethanolandmethanol,ontheotherhand,haveimportantadvantagesoverothercarbon-basedalternativefuels:theyhaveahigherenergycontentpervolumeandwouldrequireminimalchangesintheexistingnetworkfordistributingmotorfuel.Ethanoliscommonlyusedasagasolinesupplement,butitiscurrentlyabouttwiceasexpensiveasmethanol,thelowcostofwhichisoneofitsattractivefeatures.Methanol’smostattractivefeature,however,isthatitcanreducebyabout90percentthevehicleemissionsthatformozone,themostseriousurbanairpollutant.Likeanyalternativefuel,methanolhasitscritics.Yetmuchofthecriticismisbasedontheuseof“gasolineclone”vehiclesthatdonotincorporateeventhesimplestdesignimprovementsthataremadepossiblewiththeuseofmethanol.Itistrue,forexample,thatagivenvolumeofmethanolprovidesonlyaboutone-halfoftheenergythatgasolineanddieselfueldo;otherthingsbeingequal,thefueltankwouldhavetobesomewhatlargerandheavier.However,sincemethanol-fueledvehiclescouldbedesignedtobemuchmoreefficientthan“gasolineclone”vehiclesfueledwithmethanol,theywouldneedcomparativelylessfuel.VehiclesincorporatingonlythesimplestoftheengineimprovementsthatmethanolfeasiblewouldstillcontributetoanimmediatelesseningofurbanairTheauthorofthepassageisprimarilyconcernedcounteringaflawedargumentthatdismissesapossiblesolutiontoareconcilingcontradictorypointsofviewaboutthenatureofaidentifyingthestrengthsofpossiblesolutionstoadiscussingaproblemandarguinginfavorofonesolutionto3(E)outlining(E)outliningaplanofactiontosolveaproblemanddiscussingtheobstaclesblockingthatplanAccordingtothepassage,incompletecombustionismorelikelytooccurwithgasolinethanwithanalternativefuelbecausethecombustionofgasolinereleasesphotochemicallyactivethecombustionofgasolineinvolvesanintricateseriesofgasolinemoleculeshaveasimplemoleculargasolineiscomposedofsmallgasolineisacarbon-basedThepassagesuggestswhichofthefollowingaboutairFurtherattemptstoreduceemissionsfromgasoline-fueledvehicleswillnothelplowerurbanair-pollutionlevels.Attemptstoreducethepollutantsthatanindividualgasoline-fueledvehicleemitshavebeenlargelyunsuccessful.Fewseriousattemptshavebeenmadetoreducetheamountofpollutantsemittedbygasoline-fueledvehicles.Pollutantsemittedbygasoline-fueledvehiclesarenotthemostcriticalsourceofurbanairpollution.Reductionsinpollutantsemittedbyindividualvehicleshavebeenoffsetbyincreasesinpollutionfromsourcesotherthangasoline-fueledvehicles.WhichofthefollowingmostcloselyparallelsthesituationdescribedinthefirstsentenceoftheAlthoughatownreducesitspublicservicesinordertoavoidataxincrease,thetown’staxrateexceedsthatofothertownsinthesurroundingarea.Althoughastatepassesstrictlawstolimitthetypeoftoxicmaterialthatcanbedisposedofinpubliclandfills,illegaldumpingcontinuestoincrease.Althoughatown’scitizensreducetheirindividualuseofwater,thetown’swatersuppliescontinuetodwindlebecauseofasteadyincreaseinthetotalpopulationofthetown.Althoughacountryattemptstoincreasethesaleofdomesticgoodsbyaddingataxtothepriceofimportedgoods,thesaleofimportedgoodswithinthecountrycontinuestoincrease.Althoughacountryreducesthespeedlimitonitsnationalhighways,thenumberoffatalitiescausedbyautomobileaccidentscontinuestoincrease.TheauthordescribeswhichofthefollowingasthemostappealingfeatureofItissubstantiallylessexpensivethanItcouldbeprovidedtoconsumersthroughtheexistingmotorfuel4IthasaIthasahigherenergycontentthanotheralternativeItsusewouldmakedesignimprovementsinindividualvehiclesItsusewouldsubstantiallyreduceozoneItcanbeinferredfromthepassagethatavehiclespecificallydesignedtousemethanolforfuelbesomewhatlighterintotalbodyweightthanaconventionalvehiclefueledwithgasolinebemoreexpensivetooperatethanaconventionalvehiclefueledwithhavealargerandmorepowerfulenginethanaconventionalvehiclefueledwithgasolinehavealargerandheavierfueltankthana“gasolineclone”vehiclefueledwithmethanolaveragemoremilespergallonthana“gasolineclone”vehiclefueledwithItcanbeinferredthattheauthorofthepassagemostlikelyregardsthecriticismofmethanolinthelastparagraphasflawedbecauseoftheassumptionsonwhichitisinapplicablebecauseofaninconsistencyinthecritics’misguidedbecauseofitsexclusivelytechnologicalinaccuratebecauseitignoresconsumers’invalidbecauseitreflectsthepersonalbiasofthe2.长江水稻新题Sincethe1970s,archaeologicalsitesinChina'sYangtzeRiverregionhaveyieldedevidenceofsophisticatedrice-farmingsocietiesthatpredatesignsofricecultivationelsewhereinEastAsiabyathousandyears.Beforethisevidencewasdiscovered,ithadgenerallybeenassumedthatricefarmingbeganfarthertothesouth.Thisscenariowasbasedbothonthegeographicrangeofwildorfree-livingrice,whichwasnotthoughttoextendasfarnorthastheYangtze,andonarchaeologicalrecordsofveryearlydomesticricefromSoutheastAsiaandIndia(nowknowntobenotsooldasfirstreported).Proponentsofthesouthern-origintheorypointoutthatearlyrice-farmingsocietiesalongtheYangtzewerealreadyhighlydevelopedandthatevidenceforthefirststageofricecultivationismissing.Theyarguethatthefirsthunter-gathererstodevelopriceagriculturemusthavedonesointhissouthernzone,withintheapparentpresent-daygeographicrangeofwildrice.5YetwhilemoststrandsofwildriceYetwhilemoststrandsofwildricereportedina1984surveywereconcentratedtothesouthoftheYangtzedrainage,twonorthernoutlierpopulationswerealsodiscoveredinprovincesalongthemiddleandlowerYangtze,evidencethattheYangtzewetlandsmayfallwithinboththepresent-dayandthehistoricalgeographicrangesofrice'swild2.1.Whichofthefollowing,iftrue,wouldmostclearlyunderminetheconclusionthatthemakesbasedonthe1984AreassouthoftheYangtzebasincurrentlyhavelesswild-ricehabitatthantheyonceSurveyssince1984haveshownwildricepopulationsalongtheupperYangtzeaswellasalongthemiddleandlowerYangtze.ThepopulationsofwildricealongtheYangtzerepresentstrainsofwildricethatmigratedtothenorthrelativelyrecently.Earlyrice-farmingsocietiesalongtheYangtzewerenotashighlydevelopedasarchaeologistsonceInEastAsia,thehistoricalgeographicrangeofwildricewasmoreextensivethanthepresent-geographicrange2.2.Basedonthepassage,skepticsoftheideathatricecultivationbeganintheYangtzeRiverregioncanpointtowhichofthefollowingforsupport?Lackofevidencesupportingtheexistenceofrice-farmingsocietiesalongtheYangtzeatanearlyLackofevidenceregardingtheinitialstagesofricecultivationintheYangtzeRecentdiscoveriespertainingtothehistoricalgeographicrangeofrice'swildNewinformationregardingthedatesofveryearlydomesticricefromSoutheastNewtheoriespertainingtohowhunter-gatherersfirstdevelopedriceagricultureinEast3.Whichofthefollowingcanbeinferredfromthepassageaboutthe“southern-originThetheoryisbasedonanunconventionalunderstandingofhowhunter-gatherersfirstdevelopedriceagriculture.Thetheoryfailstotakeintoaccounttheapparentfactthatevidenceforthefirststageofricecultivationinthenorthismissing.Thetheorywasdevelopedprimarilyinresponsetoa1984surveyofwildrice'sgeographicReassessmentofthedatesofsomearchaeologicalevidencehasunderminedsupportfortheEvidenceofsophisticatedrice-farmingsocietiesintheYangtzeregionprovidessupportforthe3.TheColor相关文章：LSAT22SECTION6ThepublicationofTheColorPurpletransformedThepublicationofTheColorPurpletransformedAliceWalkerfromanindubitablyseriousblackwriterwhosefictionbelongedtoatraditionofgritty,ifoccasionally"magical,"realismintoapopularnovelistwithalltheperquisitesanddrawbacksattendantonthatposition.UnlikeeitherTheThirdLifeofGrangeCopland(1970)orMeridian(1976),TheColorPurplegainedimmediateandwidespreadpublicacceptance,winningboththePulitzerPrizeandtheAmericanBookAwardfor1982-83.Atthesametime,however,itgeneratedimmediateandwidespreadcriticaluneaseoverwhatappearedtobemanifestflawsinitscomposition.RobertTowers,writingintheNewYorkReviewofBooks,concludedthatontheevidenceofTheColorPurple"AliceWalkerstillhasalottolearnaboutplottingandstructuringwhatisclearlyintendedtobearealisticnovel."Hisopinionwassharedbymanyreviewers,whopointedoutvariouslythatinthelastthirdofthebookthenarrator-protagonistCelieandherfriendsarepropelledtowardafairytalehappyendingwithmorevelocitythancredibility;thatthelettersfromNettie,withtheirdisconcertinglyliteratedepictionsoflifeinanAfricanvillage,intrudeintothemiddleofthemainactionwithlittleapparentmotivationorwarrant;andthatthedeviceoftheletterstoGodisespeciallyunrealisticinasmuchasitforegoestheconcretizingdetailsthattraditionallyhavegiventheepistolatory书信体的formitspeculiarverisimilitude:thesecretwriting-place,thecache,therusestoenablepostingletters,andespeciallythelettersreceivedin4.socialAlthoughsociallearning（通过模仿其它个体的行为来学会某种行为）iswelldocumentedamongfish,fewstudieshaveinvestigatedsociallearningwithinadevelopmentalcontextinthesetaxa.Ratherthaninvestigatingthedevelopmentofaparticularskill,Chapman,Ward,andKrauseinvestigatedtheroleofgroupdensityduringdevelopmentinlaterforagingsuccessinlaboratory-housedguppies.Whenraisedwithasmallnumberofconspecifics（同种生物）,guppieswerequickertolocatefoodbyfollowingatrainedadultguppythanwereguppiesraisedinlargegroupsThiscounterintuitivefindingisexplainedbythefactthatguppiesrearedinthehigh-densityconditionwerelesslikelytoshoal（与群体一起游动）withothersand,therefore,werelesslikelytolearnthebenefitsofsociallearning.Instead,fishrearedinhigh-densitysituationsmaylearnthatconspecificsaretobeviewedascompetitors,ratherthanaspotentialsourcesofadaptiveinformationThisfindingsuggeststhatatleastforguppiestheearlysocialenvironmentmayhaveaneffectonthecapacityforsociallearning,ifnotonthesocially5.美洲人起源新题RecentdiscoveriesinNewWorldarchaeologyalongwithnewscientificmethodsforanalyzingdatahaveledtonewideasregardingtheoriginofthefirstpeoplesoftheAmericasandtheirtimeofThetraditionaltheoryheldthatthefirstAmericanscrossedthelandbridgefromSiberiatoAlaskaaround11,500yearsagoandfollowedan"ice-freecorridor"betweentwolargeCanadianicesheets(theLaurentideandCordilleran)toreachunglaciatedlandstothesouth.Thesefirstinhabitants,whosearchaeologicalsitesarescatteredacrossNorthandSouthAmerica,werecalledtheClovis7namedafterthetownnamedafterthetowninNewMexicowheretheirflutedspearpointsusedforhuntingmammothfirstfoundinThereisnowconvincingevidenceofhumanhabitationsitesthatdateearlierthantheCloviscultureincludingsiteslocatedinSouthAmerica.MonteVerde,awell-studiedsitelocatedalongarivernearsoutherncentralChile,dates12,500yearsago.Thissitecontainstheburiedremnantsofdwellings,stonetoolsincludinglargebifacialprojectilepoints,andpreservedmedicinalandedibleplants.Howdidpeoplemanagetosettlethisfarsouthatsuchanearlydate?Acoastalmigrationrouteisnowgainingmoreacceptance,ratherthantheolderviewofsmallbandsmovingonfootacrossthemiddleofthelandbridgebetweenSiberiaandAlaskaandintothecontinents.EmergingevidencesuggeststhatpeoplewithboatsmovedalongthePacificcoastintoAlaskaandnorthwesternCanadaandeventuallysouthtoPeruandChileby12,500yearsago—andperhapsmuchearlier.ArchaeologicalevidenceinAustralia,Melanesia,andJapanindicateboatswereinuseasfarbackas25,000to40,000yearsago.Searouteswouldhaveprovidedabundantfoodresourcesandeasierandfastermovementthanlandroutes.Manycoastalareaswereunglaciatedatthistime,providingopportunitiesforlandfallalongtheway.SeveralearlysitesalongthecoastofCanada,California,Peru,Ecuador,andChiledatebetween10,000and12,000yearsago.Manypotentialcoastalsitesarenowsubmerged,making6.HoneybeefungalIngestionoffoodcontainingsporesofthepathogenAscosphaeraapiscausesafatalfungaldiseaseknownaschalkbroodinhoneybeelarvae.However,larvaemustbechilledtoabout30°C(normalbrood-combtemperatureis33-36°C)forthediseasetodevelop.Accordingly,chalkbroodismostcommoninspringandinsmallcolonies.Arecentstudyrevealedthathoneybeesresponsibleforhive-temperaturemaintenancepurposelyraisedthehives’temperaturewhencolonieswereinoculatedwithA.apisthis“fever,”orup-regulationoftemperature,occurredbeforeanylarvaedied,suggestingthattheresponseispreventativeandthateitherhoneybeeworkersdetecttheinfectionbeforesymptomsarevisibleorlarvaecommunicatetheingestionofthepathogen.Temperaturereturnedtonormalbytheendofthestudy,suggestingthatincreasedtemperatureisnotoptimalwhenbroodsarenotinfected,aswellasthatthefeverdoesnotresultmerelyfromnormalcolonygrowth(i.e.,anincreaseinthenumberofworkersavailablefortemperature6.1.Theprimarypurposeofthepassageisdiscussthefindingsandimplicationsofaparticularillustrateaprocessthatformerlyhadbeenoutlinethemethodsusedtoinvestigateaprovideevidencetosupportacontroversialcontrastalternativeinterpretationsofcertain6.2.Accordingtothepassage,researchersconcludedthatfeverinhoneybeecoloniesispreventativebecausetheirstudyshowedthatsuchfever(A)doesnotoccurwhenhivetemperaturesarewithinnormal8protestsadultbeesfromcontractingprotestsadultbeesfromcontractingchalkbroodoccurspriortothedeathofanyismorelikelytooccurinspringthanindoesnothaveaneffectonuninfected6.3.Thepassageimpliesthatifhivetemperaturehadnotreturnedtonormalbytheendofthestudyinquestion,aprobableconclusionoftheresearcherswouldhavebeenthatup-regulationoftemperatureisapreventativemeasureagainsthoneybeesareincapableofpurposelyraisinghiveA.apiscannotbecompletelyeradicatedthroughup-regulationoftemperaturehoneybeelarvaehaveamechanismtoalertadulthoneybeestothepresenceofA.honeybeelarvaemaybenefitfromincreasedhivetemperatureevenwhenthereisnoA.apis6.4.Accordingtothepassage,whichofthefollowingistrueofchalkbroodinfectionamonghoneybeelarvae？Larvaeinsmallcoloniesaremorelikelytopasstheinfectiontoadulthoneybeesthanarelarvaeinlargeones.Infectionwithchalkbroodinduceslarvaetoraisetheirhive’sTheinfectionismorelikelytoaffectlarvaeinwinterthaninLarvaefailtodevelopsymptomsofthediseasewhentheirbrood–combtemperatureremainswithinthenormalrange.Infectedlarvaeexhibitvisiblesymptomsofdiseaseforasignificanttimebefore7.十四修正案199410月BTheFourteenthAmendmenttotheUnitedStatesConstitution,ratifiedin1868,prohibitsstategovernmentsfromdenyingcitizensthe“equalprotectionofthelaws.”Althoughpreciselywhattheframersoftheamendmentmeantbythisequalprotectionclauseremainsunclear,allinterpretersagreethattheframers’immediateobjectivewastoprovideaconstitutionalwarrantfortheCivilRightsActof1866,whichguaranteedthecitizenshipofallpersonsbornintheUnitedStatesandsubjecttoUnitedStatesjurisdiction.Thisdeclaration,whichwasechoedinthetextoftheFourteenthAmendment,wasdesignedprimarilytocountertheSupremeCourt’srulinginDredScottv.SandfordthatBlackpeopleintheUnitedStatescouldbedeniedcitizenship.TheactwasvetoedbyPresidentAndrewJohnson,whoarguedthattheThirteenthAmendment,whichabolishedslavery,didnotprovideCongresswiththeauthoritytoextendcitizenshipandequalprotectiontothefreedslaves.AlthoughCongresspromptlyoverrodeJohnson’sveto,supportersoftheactsoughttoensureitsconstitutionalfoundationswiththepassageoftheFourteenthThebroadlanguageoftheamendmentstronglysuggeststhatitsframerswereproposingtowriteintotheConstitutionnotalaundrylistofspecificcivilrightsbutaprincipleofequalcitizenshipthat9forbidsorganizedsocietyfromforbidsorganizedsocietyfromtreatinganyindividualasamemberofaninferiorclass.Yetforthefirsteightdecadesoftheamendment’sexistence,theSupremeCourt’sinterpretationoftheamendmentbetrayedthisidealofequality.IntheCivilRightsCasesof1883,forexample,theCourtinventedthe“stateaction”limitation,whichassertsthat“private”decisionsbyownersofpublicaccommodationsandothercommercialbusinessestosegregatetheirfacilitiesareinsulatedfromthereachoftheFourteenthAmendment’sguaranteeofequalprotectionundertheAftertheSecondWorldWar,ajudicialclimatemorehospitabletoequalprotectionclaimsculminatedintheSupremeCourt’srulinginBrownv.BoardofEducationthatraciallysegregatedschoolsviolatedtheequalprotectionclauseoftheFourteenthAmendment.TwodoctrinesembracedbytheSupremeCourtduringthisperiodextendedtheamendment’sreach.First,theCourtrequiredespeciallystrictscrutinyoflegislationthatemployeda“suspectclassification,”meaningdiscriminationagainstagroupongroundsthatcouldbeconstruedasracial.ThisdoctrinehasbroadenedtheapplicationoftheFourteenthAmendmenttoother,nonracialformsofdiscrimination,forwhilesomejusticeshaverefusedtofindanylegislativeclassificationotherthanracetobeconstitutionallydisfavored,mosthavebeenreceptivetoargumentsthatatleastsomenonracialdiscriminations,sexualdiscriminationinparticular,are“suspect”anddeservethisheightenedscrutinybythecourts.Second,theCourtrelaxedthestateactionlimitationontheFourteenthAmendment,bringingnewformsofprivateconductwithintheamendment’s7.1.WhichofthefollowingbestdescribesthemainideaoftheBypresentingalistofspecificrights,framersoftheFourteenthAmendmentwereattemptingtoprovideaconstitutionalbasisforbroadjudicialprotectionoftheprincipleofequalcitizenship.OnlyaftertheSupremeCourtadoptedthesuspectclassificationapproachtoreviewingpotentiallydiscriminatorylegislationwastheapplicabilityoftheFourteenthAmendmentextendedtoincludesexualdiscrimination.NotuntilaftertheSecondWorldWardidtheSupremeCourtbegintointerprettheFourteenthAmendmentinamannerconsistentwiththeprincipleofequalcitizenshipthatitexpresses.InterpretersoftheFourteenthAmendmenthaveyettoreachconsensuswithregardtowhatitsframersmeantbytheequalprotectionclause.AlthoughthereluctanceofjudgestoextendthereachoftheFourteenthAmendmenttononracialdiscriminationhasbetrayedtheprincipleofequalcitizenship,theSupremeCourt’suseofthestateactionlimitationtoinsulateprivateactivityfromtheamendment’sreachhasbeenmore7.2.ThepassagesuggeststhattheprincipaleffectofthestateactionlimitationwasallowsomediscriminatorypracticestocontinueunimpededbytheFourteenthinfluencetheSupremeCourt’srulinginBrownv,BoardofprovideexpandedguidelinesdescribingprohibitedprohibitstatesfromenactinglawsthatviolatedtheintentoftheCivilRightsActofshifttostategovernmentstheresponsibilityforenforcementoflawsprohibitingdiscriminatory7.3.Theauthor’sposition7.3.Theauthor’spositionregardingtheintentoftheframersoftheFourteenthAmendmentwouldbemostseriouslyunderminedifwhichofthefollowingweretrue?TheframershadanticipatedstateactionlimitationsastheyaredescribedintheTheframershadmerelysoughttopreventdiscriminatoryactsbyfederalTheframerswereconcernedthattheCivilRightsActof1866wouldbeoverturnedbytheSupremeTheframerswereawarethatthephrase“equalprotectionofthelaws”hadbroadTheframersbelievedthatracialaswellasnon-racialformsofdiscriminationwere7.4.Accordingtothepassage,theoriginalproponentsoftheFourteenthAmendmentwereprimarilyconcernedwithdetailingtherightsaffordedbytheprincipleofequalprovidingsupportintheConstitutionforequalprotectionforallcitizensoftheUnitedclosingaloopholethatcouldbeusedtodenyindividualstherighttosueforenforcementoftheircivilrightsassertingthatthecivilrightsprotectedbytheConstitutionincludednonracialdiscriminationaswellasracialdiscriminationgrantingstategovernmentsbroaderdiscretionininterpretingtheCivilRightsActof7.5.TheauthorimpliesthattheFourteenthAmendmentmightnothavebeenenactedCongress’authoritywithregardtolegislatingcivilrightshadnotbeentheframershadanticipatedtheSupremeCourt’srulinginBrownv.Boardoftheframershadbelievedthatitwouldbeusedindecidingcasesofdiscriminationinvolvingnon-racialgroupsmoststategovernmentshadbeenwillingtoprotectcitizens’civilitsessentialelementshadnotbeenimplicitintheThirteenth7.6.Accordingtothepassage,whichofthefollowingmostaccuratelyindicatesthesequenceoftheeventslistedbelow?CivilRightsActofDredScottv.FourteenthVetobyPresidentI,II,III,I,IV,II,I,IV,III,II,I,IV,III,II,I,7.7.Whichofthefollowingcanbeinferredaboutthesecondofthetwodoctrinesreferredtoinlines39-41ofthepassage?(A)ItcausedsomejusticestorulethatalltypesofdiscriminationareprohibitedbytheItshiftedthefocusItshiftedthefocusoftheSupremeCourtfromracialtononracialItnarrowedtheconcernoftheSupremeCourttolegislationthatemployedasuspectItcausedlegislatorswhowerewritingnewlegislationtorejectlanguagethatcouldbeconstruedaspermittingracialdiscrimination.Itmadeitmoredifficultforcommercialbusinessestopracticeracial8.MayaTounderstandtheancientMayanpeoplewholivedintheareathatistodaysouthernMexicoandCentralAmericaandtheecologicaldifficultiestheyfaced,onemustfirstconsidertheirenvironment,whichwethinkofas“jungle"or'tropicalrainforest."Thisviewisinaccurate,andthereasonprovestobeimportant.Properlyspeaking,tropicalrainforestsgrowinhigh-rainfallequatorialareasthatremainwetorhumidallyearround.ButtheMayahomelandliesmorethansixteenhundredkilometersfromtheequator,atlatitudes17to22degreesnorth,inahabitattermeda“seasonaltropicalforest."Thatis,whiletheredoestendtobearainyseasonfromMaytoOctober,thereisalsoadryseasonfromJanuarythroughApril.Ifonefocusesonthewetmonths,onecallstheMayahomelanda"seasonaltropicalforest";ifonefocusesonthedrymonths,onecouldinsteaddescribeitasa"seasonalFromnorthtosouthintheYucatanPeninsula,wheretheMayalived,rainfallrangesfrom18to100inches(457to2,540millimeters)peryear,andthesoilsbecomethicker,sothatthesouthernpeninsulawasagriculturallymoreproductiveandsupporteddenserpopulations.ButrainfallintheMayahomelandisunpredictablyvariablebetweenyears;somerecentyearshavehadthreeorfourtimesmorerainthanotheryears.Asaresult,modernfarmersattemptingtogrowcornintheancientMayahomelandshavefacedfrequentcropfailures,especiallyinthenorth.TheancientMayawerepresumablymoreexperiencedanddidbetter,butneverthelesstheytoomusthavefacedrisksofcropfailuresfromdroughtsandAlthoughsouthemMayaareasreceivedmorerainfallthannorthernareas,problemsofwaterwereparadoxicallymoresevereinthewetsouth.WhilethatmadethingshardforancientMayalivinginthesouth,ithasalsomadethingshardformodemarchaeologistswhohavedifficultyunderstandingwhyancientdroughtscausedbiggerproblemsinthewetsouththaninthedrynorth.ThelikelyexplanationisthatanareaofundergroundfreshwaterunderliestheYucatanPeninsula,butsurfaceelevationincreasesfromnorthtosouth,sothatasonemovessouththelandsurfaceliesincreasinglyhigherabovethewatertable.InthenorthernpeninsulatheelevationissufficientlylowthattheancientMayawereabletoreachthewatertableatdeepsinkholescalledcenotes,oratdeepcaves.Inlow-elevationnorthcoastalareaswithoutsinkholes,theMayawouldhavebeenabletogetdowntothewatertablebydiggingwellsupto75feet(22meters)deep.Butmuchofthesouthliestoohighabovethewatertableforcenotesorwellstoreachdowntoit.Makingmattersworse,mostoftheYucatanPeninsulaconsistsofkarst,aporoussponge-likelimestoneterrainwhererainrunsstraightintothegroundandwherelittleornosurfacewaterremainsavailable.HowdidthosedensesouthernMayaHowdidthosedensesouthernMayapopulationsdealwiththeresultingwaterproblem?Itinitiallysurprisesusthatmanyoftheircitieswerenotbuiltnexttotheriversbutinsteadonhighterraininrollinguplands.TheexplanationisthattheMayaexcavateddepressions,ormodifiednaturaldepressions,andthenpluggedupleaksinthekarstbyplasteringthebottomsofthedepressionsinordertocreatereservoirs,whichcollectedrainfromlargeplasteredcatchmentbasinsandstoreditforuseinthedryseason.Forexample,reservoirsattheMayacityofTikalheldenoughwatertomeetthedrinkingwaterneedsofabout10,000peopleforaperiodof18months.AtthecityofCobatheMayabuiltdikesaroundalakeinordertoraiseitslevelandmaketheirwatersupplymorereliable.ButtheinhabitantsofTikalandothercitiesdependentonreservoirsfordrinkingwaterwouldstillhavebeenindeeptroubleif18monthspassedwithoutraininaprolongeddrought.Ashorterdroughtinwhichtheyexhaustedtheirstoredfoodsuppliesmightalreadyhavegottenthemindeeptrouble,becausegrowingcropsrequiredrainratherthan9.鹿背上的WhichoffollowingmostlogicallycompletestheThelastmembersofanow-extinctspeciesofaEuropeanwilddeercalledthegiantdearlivedinIrelandabout16,000yearsago.PrehistoriccavepaintingsinFrancedepictthisanimalashavingalargehumponitsback.Fossilsofthisanimal,however,donotshowanyhump.Nevertheless,thereisnoreasontoconcludethatthecavepaintingsarethereforeinaccurateinthisregard,since AsomeprehistoriccavepaintingsinFrancealsodepictotheranimalsashavingahumpBfossilsofthegiantdeeraremuchmorecommoninIrelandthaninFranceCanimalhumpsarecomposedoffattytissue,whichdosenotDthecavepaintingsofthegiantdeerwerepaintedwellbefore16,000yearsEonlyonecurrentlyexistingspecie