At______,photographyisachemicalprocess,duringwhichalight-sensitivematerialisalteredwhenexposedtolight.

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.

汉译英：生活就像一杯红酒，热爱生活的人会从其中品出无穷无尽的美妙。将它握在手中仔细观察，它的暗红色中有血的感觉，那正是生命的痕迹。抿一口留在口中回味，它的甘甜中有一丝苦涩，如人生一般复杂迷离。喝一口下肚，余香沁人心脾，让人终身受益。红酒越陈越美味，生活越丰富越美好。当人生走向晚年，就如一瓶待开封的好酒，其色彩是沉静的，味道中充满慷慨与智慧。

Manyartistspredictthatthisbrilliantyoungactor__tobeashinningstar.

IamsorryIhavenotimeatpresentto____moredetailorgiveyouanaccountofothercitiesofinterest.