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.
ABDDD
暂无解析
—Are you hungry now?
—_______. I have just had two bowls of rice.
All their __ have been shown up by their own deeds.
In some countries where racial prejudice is acute, violence has so come to be taken for granted as a means of solving differences, that it is not even questioned. There are countries where the white man imposes his rule by brute force; there are countries where the black man protests by setting fire to cities and by looting and pillaging. Important people on both sides, who would in other respects appear to be reasonable men, get up and calmly argue in favor of violence – as if it were a legitimate solution, like any other. What is really frightening, what really fills you with despair, is the realization that when it comes to the crunch, we have made no actual progress at all. We may wear collars and ties instead of war-paint, but our instincts remain basically unchanged. The whole of the recorded history of the human race, that tedious documentation of violence, has taught us absolutely nothing. We have still not learnt that violence never solves a problem but makes it more acute. The sheer horror, the bloodshed, the suffering mean nothing. No solution ever comes to light the morning after when we dismally contemplate the smoking ruins and wonder what hit us. The truly reasonable men who know where the solutions lie are finding it harder and herder to get a hearing. They are despised, mistrusted and even persecuted by their own kind because they advocate such apparently outrageous things as law enforcement. If half the energy that goes into violent acts were put to good use, if our efforts were directed at cleaning up the slums and ghettos, at improving living-standards and providing education and employment for all, we would have gone a long way to arriving at a solution. Our strength is sapped by having to mop up the mess that violence leaves in its wake. In a well-directed effort, it would not be impossible to fulfill the ideals of a stable social programme. The benefits that can be derived from constructive solutions are everywhere apparent in the world around us. Genuine and lasting solutions are always possible, providing we work within the framework of the law. Before we can even begin to contemplate peaceful co-existence between the races, we must appreciate each other's problems. And to do this, we must learn about them: it is a simple exercise in communication, in exchanging information. "Talk, talk, talk," the advocates of violence say, "all you ever do is talk, and we are none the wiser." It's rather like the story of the famous barrister who painstakingly explained his case to the judge. After listening to a lengthy argument the judge complained that after all this talk, he was none the wiser. "Possible, my lord," the barrister replied, "none the wiser, but surely far better informed." Knowledge is the necessary prerequisite to wisdom: the knowledge that violence creates the evils it pretends to solve.
1. What is the best title for this passage?
[A] Advocating Violence.
[B] Violence Can Do Nothing to Diminish Race Prejudice.
[C] Important People on Both Sides See Violence As a Legitimate Solution.
[D] The Instincts of Human Race Are Thirsty for Violence.
2. Recorded history has taught us
[A] violence never solves anything. [B] nothing. [C] the bloodshed means nothing. [D]everything.
3. It can be inferred that truly reasonable men
[A] can't get a hearing.
[B] are looked down upon.
[C] are persecuted.
[D] Have difficulty in
advocating law enforcement.
4. "He was none the wiser" means
[A] he was not at all wise in listening.
[B] He was not at all wiser than nothing before.
[C] He gains nothing after listening.
[D] He makes no sense of the argument.
5. According the author the best way to solve race prejudice is
[A] law enforcement. [B] knowledge. [C] nonviolence. [D] Mopping up the violent mess.
You ’d better sing. It doesn’t ______ whether you can sing well or not.
Thereis______littleinformationabouthimthatwehave______muchdifficultyfindinghim.