Is Tom at school today?No, He ’s at home ______ he has a bad cold.
更新时间:2024-11-24 04:47:38 A、becauseA
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WeexpectMr.Whitewill____ClassOnewhenMissJaneretires.
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.
____beforewedepartthedayaftertomorrow,weshouldhaveawonderfuldinnerparty.
Writing:
“Traditionandmodernizationareincompatible.Onemustchoosebetweenthem”.Towhatdegreedoyouagreewiththisstatement?Writeanessayofabout400words.
Inthefirstpartofyouressayyoushouldstateclearlyyourmainargument,andinthesecondpartyoushouldsupportyourargumentwithappropriatedetails.Inthelastpartyoushouldbringwhatyouhavewrittentoanaturalconclusionormakeasummary.
Youshouldsupplyanappropriatetitleforyouressay.
Markswillbeawardedforcontent,organization,grammarandappropriateness.Failuretofollowtheaboveinstructionsmayresultinalossofmarks.
汉译英:朋友之间,情趣相投、脾气对味则合、则交,反之,则离、则绝。朋友之间再熟悉、再亲密,也不能随便过头、不恭不敬,这样,默契和平衡将被打破,友好关系将不复存在。每个人都希望拥有自己的一片私密空间,朋友之间过于随便,就容易侵入这片禁区,从而引起冲突,造成隔阂。待友不敬,有时或许只是一件小事,却可能已埋下了破坏性的种子。维持朋友亲密关系的最好办法是往来有节,互不干涉。