Nowhereinnatureisaluminumfoundfree,owingtoitsalways____withotherelements,mostcommonlywithoxygen.

Insomecountrieswhereracialprejudiceisacute,violencehassocometobetakenforgrantedasameansofsolvingdifferences,thatitisnotevenquestioned.Therearecountrieswherethewhitemanimposeshisrulebybruteforce;therearecountrieswheretheblackmanprotestsbysettingfiretocitiesandbylootingandpillaging.Importantpeopleonbothsides,whowouldinotherrespectsappeartobereasonablemen,getupandcalmlyargueinfavorofviolence–asifitwerealegitimatesolution,likeanyother.Whatisreallyfrightening,whatreallyfillsyouwithdespair,istherealizationthatwhenitcomestothecrunch,wehavemadenoactualprogressatall.Wemaywearcollarsandtiesinsteadofwar-paint,butourinstinctsremainbasicallyunchanged.Thewholeoftherecordedhistoryofthehumanrace,thattediousdocumentationofviolence,hastaughtusabsolutelynothing.Wehavestillnotlearntthatviolenceneversolvesaproblembutmakesitmoreacute.Thesheerhorror,thebloodshed,thesufferingmeannothing.Nosolutionevercomestolightthemorningafterwhenwedismallycontemplatethesmokingruinsandwonderwhathitus.Thetrulyreasonablemenwhoknowwherethesolutionsliearefindingitharderandherdertogetahearing.Theyaredespised,mistrustedandevenpersecutedbytheirownkindbecausetheyadvocatesuchapparentlyoutrageousthingsaslawenforcement.Ifhalftheenergythatgoesintoviolentactswereputtogooduse,ifoureffortsweredirectedatcleaninguptheslumsandghettos,atimprovingliving-standardsandprovidingeducationandemploymentforall,wewouldhavegonealongwaytoarrivingatasolution.Ourstrengthissappedbyhavingtomopupthemessthatviolenceleavesinitswake.Inawell-directedeffort,itwouldnotbeimpossibletofulfilltheidealsofastablesocialprogramme.Thebenefitsthatcanbederivedfromconstructivesolutionsareeverywhereapparentintheworldaroundus.Genuineandlastingsolutionsarealwayspossible,providingweworkwithintheframeworkofthelaw.Beforewecanevenbegintocontemplatepeacefulco-existencebetweentheraces,wemustappreciateeachother'sproblems.Andtodothis,wemustlearnaboutthem:itisasimpleexerciseincommunication,inexchanginginformation."Talk,talk,talk,"theadvocatesofviolencesay,"allyoueverdoistalk,andwearenonethewiser."It'sratherlikethestoryofthefamousbarristerwhopainstakinglyexplainedhiscasetothejudge.Afterlisteningtoalengthyargumentthejudgecomplainedthatafterallthistalk,hewasnonethewiser."Possible,mylord,"thebarristerreplied,"nonethewiser,butsurelyfarbetterinformed."Knowledgeisthenecessaryprerequisitetowisdom:theknowledgethatviolencecreatestheevilsitpretendstosolve.

1.Whatisthebesttitleforthispassage?

[A]AdvocatingViolence.

[B]ViolenceCanDoNothingtoDiminishRacePrejudice.

[C]ImportantPeopleonBothSidesSeeViolenceAsaLegitimateSolution.

[D]TheInstinctsofHumanRaceAreThirstyforViolence.

2.Recordedhistoryhastaughtus

[A]violenceneversolvesanything.[B]nothing.[C]thebloodshedmeansnothing.[D]everything.

3.Itcanbeinferredthattrulyreasonablemen

[A]can'tgetahearing.

[B]arelookeddownupon.

[C]arepersecuted.

[D]Havedifficultyin

advocatinglawenforcement.

4."Hewasnonethewiser"means

[A]hewasnotatallwiseinlistening.

[B]Hewasnotatallwiserthannothingbefore.

[C]Hegainsnothingafterlistening.

[D]Hemakesnosenseoftheargument.

5.Accordingtheauthorthebestwaytosolveraceprejudiceis

[A]lawenforcement.[B]knowledge.[C]nonviolence.[D]Moppinguptheviolentmess.

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.

GreatasNewtonwas,manyofhisideas____todayandarebeingmodifiedbytheworkofscientistsofourtime.

I’dratheryou____bytrainbecausetheweatherforecastsaidtherewouldbeheavysnowtomorrow.