AsGilbertWhite，Darwin，andothersobservedlongago，allspeciesappeartohavetheinnatecapacitytoincreasetheirnumbersfromgenerationtogeneration.Thetaskforecologistsistountangletheenvironmentaandbiologicalfactorsthatholdthisintrinsiccapacityforpopulationgrowthincheckoverthelongrun.Thegreatvarietyofdynamicbehaviorsexhibitedbydifferentpopulationmakesthistaskmoredifficult：sompopulationsremainroughlyconstantfromyeartoyear;othersexhibitregularcyclesofabundanceandscarcity;stillothersvarywildly，withoutbreaksandcrashesthatareinsomecasesplainlycorrelatedwiththeweather，andinothercasesnot.Toimposesomeorderonthiskaleidoscopeofpatterns，oneschoolofthoughtproposesdividingpopulationsintotwogroups.Theseecologistspositthattherelativelysteadypopulationshavedensity-dependentgrowthparameters;thatis，ratesofbirth，death，andmigrationwhichdependstronglyonpopulationdensity.Thehighlyvaryingpopulationshavedensity-independentgrowthparameters，withvitalratesbuffetedbyenvironmentalevents;theseratesfluctuateinawaythatiswhollyindependentofpopulationdensity.Thisdichotomyhasitsuses，butitcancauseproblemsiftakentooliterally.Foronething，nopopulationcanbedrivenentirelybydensity-independentfactorsallthetime.Nomatterhowseverelyorunpredictablybirth，death，andmigrationratesmaybefluctuatingaroundtheirlong-termaverages，iftherewerenodensity-dependenteffects，thepopulationwould，inthelongrun，eitherincreaseordecreasewithoutbound(barringamiraclebywhichgainsandlossescanceledexactly)。Putanotherway，itmaybethatonaverage99percentofalldeathsinapopulationarisefromdensity-independentcauses，andonlyonepercentfromfactorsvaryingwithdensity.Thefactorsmakinguptheonepercentmayseemunimportant，andtheircausemaybecorrespondinglyhardtodetermine.Yet，whetherrecognizedornot，theywillusuallydeterminethelong-termaveragepopulationdensity.Inordertounderstandthenatureoftheecologist’sinvestigation，wemaythinkofthedensity-dependenteffectsongrowthparametersasthesignalecologistsaretryingtoisolateandinterpret，onethattendstomakethepopulationincreasefromrelativelylowvaluesordecreasefromrelativelyhighones，whilethedensity-independenteffectsacttoproducenoiseinthepopulationdynamics.Forpopulationsthatremainrelativelyconstant，orthatoscillatearoundrepeatedcycles，thesignalcanbefairlyeasilycharacterizedanditseffectsdescribed，eventhoughthecausativebiologicalmechanismmayremainunknown.Forirregularlyfluctuatingpopulations，wearelikelytohavetoofewobservationstohaveanyhopeofextractingthesignalfromtheoverwhelmingnoise.Butitnowseemsclearthatallpopulationsareregulatedbyamixtureofdensity-dependentanddensity-independenteffectsinvaryingproportions.

1.Theauthorofthetextisprimarilyconcernedwith

[A]Discussingtwocategoriesoffactorsthatcontrolpopulationgrowthandassessingtheirrelativeimportance.

[B]Describinghowgrowthratesinnaturalpopulationsfluctuateovertimeandexplainingwhythesechangesoccur.

[C]Proposingahypothesisconcerningpopulationsizeandsuggestingwaystotestit.

[D]Posingafundamentalquestionaboutenvironmentalfactorsinpopulationgrowthandpresentingsomecurrentlyacceptedanswer.

2.Itcanbeinferredfromthetextthattheauthorconsidersthedichotomydiscussedtobe

[A]Applicableonlytoerraticallyfluctuatingpopulations.

[B]instrumental，butonlyifitslimitationsarerecognized.

[C]Dangerouslymisleadinginmostcircumstances.

[D]Acompleteandsufficientwaytoaccountforobservedphenomena.

3.tothetext，allofthefollowingbehaviorshavebeenexhibitedbydifferentpopulationsEXCEPT

[A]Roughlyconstantpopulationlevelsfromyeartoyear.

[B]Regularcyclesofincreasesanddecreasesinnumbers.

[C]Erraticincreasesinnumberscorrelatedwiththeweather.

[D]Uncheckedincreasesinnumbersovermanygenerations.

4.Thediscussionconcerningpopulationinthethirdparagraphservesprimarilyto

[A]Demonstratethedifficultiesecologistsfaceinstudyingdensity-dependentfactorslimitingpopulationgrowth.

[B]Advocatemorerigorousstudyofdensity-dependentfactorsinpopulationgrowth.

[C]Provethatthedeathratesofanypopulationareneverentirelydensity-independent.

[D]underlinetheimportanceofevensmalldensity-dependentfactorsinregulatinglong-termpopulationdensities.

5.Inthetext，theauthordoesallofthefollowingEXCEPT

[A]Citetheviewsofotherbiologists.

[B]Defineabasicproblemthatthetextaddresses.

[C]Presentconceptualcategoriesusedbyotherbiologists.

[D]Describetheresultsofaparticularstudy.

—Icametoyourofficeyesterdaymorning,butnobodywasin.

—Oh,we__________ameetinginthemeetingroom.

Thetouristtradeisbooming.Withallthiscomingandgoing，you'dexpectgreaterunderstandingodevelopbetweenthenationsoftheworld.Notabitofit!Superbsystemsofcommunicationbyair，seaandlandmakeitpossibleforustovisiteachother'scountriesatamoderatecost.Whatwasoncethe'grandtour'，reservedforonlytheveryrich，isnowwithineverybody'sgrasp?

Thepackagetourandcharteredflightsarenottobesneeredat.Moderntravelersenjoyalevelofcomfortwhichthelordsandladiesongrandtoursintheolddayscouldn'thavedreamedof.Butwhat'sthesenseofthismassexchangeofpopulationsifthenationsoftheworldremainbasicallyignorantofeachother?

Manytouristorganizationsaredirectlyresponsibleforthisstateofaffairs.Theydeliberatelysetouttoprotecttheirclientsfromtoomuchcontactwiththelocalpopulation.Themoderntouristleadsacosseted，shelteredlife.Helivesatinternationalhotels，whereheeatshisinternationalfoodandsipshisinternationaldrinkwhilehegazesatthenativesfromadistance.Conductedtourstoplacesofinterestarecarefullycensored.Thetouristisallowedtoseeonlywhattheorganizerswanthimtoseeandnomore.Astrictschedulemakesitimpossibleforthetouristtowanderoffonhisown;andanyway，languageisalwaysabarrier，soheisonlytoohappytobeprotectedinthisway.Atitsveryworst，thisleadstoanewandhideouskindofcolonization.

Thesummerquartersoftheinhabitantsoftheciteuniversitaire：aretemporarilyreestablishedontheislandofCorfu.BlackpoolisrecreatedatTorremolinoswherethetravelergoesnottoeatpaella，butfishandchips.Thesadthingaboutthissituationisthatitleadstothepersistenceofnationalstereotypes.Wedon'tseethepeopleofothernationsastheyreallyare，butaswehavebeenbroughtuptobelievetheyare.Youcantestthisforyourself.Takefivenationalities，say，French，German，English，AmericanandItalian.Nowinyourmind，matchthemwiththesefiveadjectives：musical，amorous，cold，pedantic，native.Farfromprovidinguswithanyinsightintothenationalcharacteristicsofthepeoplesjustmentioned，theseadjectivesactuallyactasbarriers.Sowhenyousetoutonyourtravels，theonlycharacteristicsyounoticearethosewhichconfirmyourpreconceptions.Youcomeawaywiththehighlyunoriginalandinaccurateimpressionthat，say，'Anglo-Saxonsarehypocrites'ofthat'Latinpeoplesshoutalot'.Youonlyhavetomakeafewforeignfriendstounderstandhowabsurdandharmfulnationalstereotypesare.Buthowcanyoumakeforeignfriendswhenthetouristtradedoesitsbesttopreventyou?Carriedtoanextreme，stereotypescanbepositivelydangerous.Wildgeneralizationsstirupracialhatredandblindustothebasicfact〞howtriteitsounds!每Thatallpeoplearehuman.Weareallsimilartoeachotherandatthesametimeallunique.

1.Thebesttitleforthispassageis

[A]Tourismcontributesnothingtoincreasingunderstandingbetweennations.

[B]Tourismistiresome.

[C]Conductedtourisdull.

[D]Tourismreallydoessomethingtoone'scountry.

2.Whatistheauthor'sattitudetowardtourism?

[A]apprehensive.[B]negative.[C]critical.[D]appreciative.

3.WhichwordinthefollowingisthebesttosummarizeLatinpeopleshoutalot?

[A]silent.[B]noisy.[C]lively.[D]active.

4.Thepurposeoftheauthor'scriticismistopointout

[A]conductedtourisdisappointing.

[B]thewayoftouringshouldbechanged.

[C]whentraveling，younoticecharacteristicswhichconfirmpreconception.

[D]nationalstereotypesshouldbechanged.

5.Whatis'grandtour'now?

[A]moderatecost.

[B]localsight-seeingisinvestigatedbythetouristorganization.

[C]peopleenjoythefirst-ratecomforts.

[D]everybodycanenjoythe'grandtour'

Oneoftherequirementsforafireisthatthematerial____toitsburningtemperature.

Youmustpayimport____oncertaingoodsbroughtintothiscountry.