As Gilbert White，Darwin ， and others observed long ago， all species appear to have theinnate capacity to increase their numbers from generation to generation. The task forecologistsis to untangle the environmentaand biologicalfactorsthat hold this intrinsiccapacity for population growth in check over the long run. The great variety of dynamicbehaviorsexhibitedby differentpopulationmakes thistaskmore difficult：sompopulations remain roughly constant from year to year; others exhibit regular cycles ofabundance and scarcity; still others vary wildly， with outbreaks and crashes that arein some cases plainly correlated with the weather， and in other cases not.To impose some order on this kaleidoscopeof patterns ， one school of thought proposesdividing populations into two groups. These ecologists posit that the relatively steadypopulations havedensity-dependent growth parameters; that is， rates ofbirth ， death ，and migrationwhich depend strongly on population density. The highly varying populationshave density-independent growth parameters， with vital rates buffeted by environmentalevents ;these rates fluctuate in a way that is wholly independent of population density.This dichotomy has its uses， but it can cause problems if taken too literally. Forone thing ， no population can be driven entirely by density-independent factors all thetime. No matter how severely or unpredictably birth， death ， and migration rates may befluctuatingaround theirlong-termaverages ， ifthere were no density-dependenteffects ，the populationwould ， in the long run ， eitherincrease or decrease without bound (barringa miracle by which gains and losses canceled exactly)。 Put another way， it may be thaton average 99 percent of all deaths in a populationarise from density-independentcauses ，and only one percent from factors varying with density.The factorsmaking up the one percentmay seem unimportant， and their cause may be correspondingly hard to determine. Yet，whether recognized or not， they will usually determine the long-term average populationdensity.In order to understand the nature of theecologist ’s investigation， we may think ofthe density-dependent effectson growth parameters as the signal ecologists are trying toisolateand interpret， one that tends to make the population increase from relativelylowvalues or decrease from relatively high ones， while the density-independent effects actto produce noise in the populationdynamics.For populationsthatremain relativelyconstant ， or that oscillate around repeated cycles， the signal can be fairly easilycharacterized and its effects described， even though the causative biological mechanismmay remain unknown. For irregularly fluctuating populations， we are likely to have toofew observations to have any hope of extracting the signal from the overwhelming noise.But it now seems clear that all populationsare regulatedby a mixture of density-dependentand density-independent effects in varying proportions.

1. The author of the text is primarily concerned with

[A] Discussing two categories of factorsthat controlpopulationgrowth and assessingtheir relative importance.

[B] Describinghow growth ratesin naturalpopulationsfluctuateover time andexplaining why these changes occur.

[C] Proposing a hypothesisconcerning population size and suggesting ways to test it.

[D] Posing a fundamental question about environmentalfactorsin populationgrowth andpresenting some currently accepted answer.

2. It can be inferred from the text that the author considers the dichotomy discussedto be

[A] Applicable only to erratically fluctuating populations.

[B] instrumental， but only if its limitations are recognized.

[C] Dangerously misleading in most circumstances.

[D] A complete and sufficient way to account for observed phenomena.

3.to the text ， allof the followingbehaviors have been exhibitedby differentpopulations EXCEPT

[A] Roughly constant population levels from year to year.

[B] Regular cycles of increases and decreases in numbers.

[C] Erratic increases in numbers correlated with the weather.

[D] Unchecked increases in numbers over many generations.

4. The discussion concerning population in the third paragraph serves primarily to

[A] Demonstrate the difficultiesecologistsface in studying density-dependentfactorslimiting population growth.

[B] Advocate more rigorous study of density-dependent factors in population growth.

[C] Prove that the death rates of any populationare never entirelydensity-independent.

[D] underline the importance of even small density-dependent factors in regulatinglong-term population densities.

5. In the text， the author does all of the following EXCEPT

[A] Cite the views of other biologists.

[B] Define a basic problem that the text addresses.

[C] Present conceptual categories used by other biologists.

[D] Describe the results of a particular study.

The foreigners _________there, but they _________the food there at first.

Roger Rosenblatt ’s book Black Fiction,in attemptingto apply literaryratherthansociopolitical criteria to its subject, successfully alters the approach taken by mostprevious studies. As Rosenblatt notes, criticism of Black writing has often served as apretextfor expounding on Black history.Addison Gayle’s recent work, for example, judgesthe value of Black fiction by overtly political standards, rating each work according tothe notions of Black identity which it propounds.Although fictionassuredly springs from politicalcircumstances ，its authors react tothose circumstances in ways other than ideological, and talking about novels and storiesprimarilyas instrumentsof ideologycircumvents much of the fictional enterprise.Rosenblatt ’s literaryanalysisdisclosesaffinitiesand connections among works of Blackfiction which solely political studies have overlooked or ignored. Writing acceptable criticism ofBlack fiction, however, presupposes giving satisfactory answers to a number of questions.First of all, is there a sufficient reason, other than the facial identity of the authors, to group together works by Black authorsSecond, how does Black fiction make itself distinct from other modern fiction with which it islargely contemporaneous Rosenblatt shows that Black fiction constitutes a distinct bodyof writingthat has an identifiable， coherent literarytradition.Looking at novels writtenby Black over the last eighty years, he discovers recurringconcerns and designs independentof chronology. These structures are thematic, and they spring, not surprisingly, from thecentralfact that the Black charactersin these novels exist in a predominantlywhite culture,whether they try to conform to that culture or rebel against it.Black Fictiondoes leave some aestheticquestions open. Rosenblatt ’s thematic analysispermits considerable objectivity; he even explicitly states that it is not his intentionto judge the merit of the various works D yet his reluctance seems misplaced, especiallysince an attempt to appraise might have led to interesting results. For instance, some ofthe novels appear to be structurallydiffuse.Is this a defect,or are the authors workingout of, or trying to forge, a different kind of aesthetic In addition, the style of someBlack novels, like JeanToomey’s Cane, verges on expressionism or surrealism; does thistechnique provide a counterpointto the prevalenttheme that portrays the fate against whichBlack heroes are pitted,a theme usuallyconveyed by more naturalisticmodes of expressionIn spite of such omissions, what Rosenblatt does include in his discussion makes foran astute and worthwhile study. Black Fiction surveys a wide variety of novels, bringingto our attention in the process some fascinating and little-known works like James WeldonJohnson’s Autobiography of an Ex-Colored Man. Its argument is tightly constructed, andits forthright, lucid style exemplifies levelheaded and penetrating criticism.

1. The author of the text is primarily concerned with __________.

[A] Evaluating the soundness of a work of criticism.[B] Comparing various critical approaches to a subject.

[C] Discussing the limitations of a particular kind of criticism.

[D] Summarizing the major points made in a work of criticism.

2. The author of the text believes that Black Fiction would have been improved hadRosenblatt __________.

[A] Evaluated more carefully the ideological andhistoricalaspects of Black fiction.

[B] Attempted to be more objective in his approach to novels and stories by Blackauthors.

[C] Explorein greaterdetailthe recurrentthematicconcerns of Black fictionthroughout its history.

[D] Assessed the relative literary merit of the novels he analyzes thematically.

3.author ’s discussion of Black Fiction can be best described as __________.

[A] Pedantic and contentious.

[B] Critical but admiring.

[C] Ironic and deprecating.

[D] Argumentative but unfocused.author of the text employs all of the following in the discussion ofRosenblatt ’s

4.book EXCEPT： __________.

[A] Rhetorical questions.

[B] Specific examples.

[C] Comparison and contrast.

[D] Definition of terms.

5. The author of the text refers to James WeldonJohnson’s Autobiography of anEx-Colored Man most probably in order to __________.

[A] point out affinitiesbetween Rosenblatt ’s method of thematic analysis and earliercriticism.

[B] Clarify the point about expressionistic style made earlier in the passage.

[C] Qualify the assessment ofRosenblatt ’s book made in the first paragraph of thepassage.

[D] give a specific example of one of the accomplishments ofRosenblatt ’s work.

The car is _____ expensive _____ he can’t buy it.

I ______ that I were a bird.