考研考博-考博英语-江苏大学模拟考试题含答案38

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1、考研考博-考博英语-江苏大学模拟考试题含答案1. 单选题If all the viruses on the planet were to disappear, a global catastrophe would supervene, and the natural ecosystems of the earth would collapse.问题1选项A.contaminateB.ensueC.disperseD.hamstring【答案】B【解析】【选项释义】A. contaminate污染；弄脏 B. ensue接着发生；因而产生C. disperse分散，散开 D. hamstring

2、妨碍；使不能正常工作【考查点】动词辨析。【解题思路】根据关键信息the natural ecosystems of the earth would collapse（地球的自然生态系统将会崩溃）可知，该句说的是因为所有的病毒消失而相继产生的后果，那么a global catastrophe would supervene表示的是“全球性的灾难将会发生”，supervene在句中表示“发生”的意思，B项词义与之相近，故该题选择B项。【干扰项排除】A、C、D项词义不符合句中所选词汇。【句意】如果地球上所有的病毒都消失了，一场全球性的灾难将会发生，地球的自然生态系统将会崩溃。2. 不定项选择题Fli

3、ght simulator (飞行模拟器) refers to any electronic or mechanical system for training airplane and spacecraft pilots and crew member by simulating fight conditions. The purpose of simulation is not to completely substitute (1) actual fight training but to thoroughly familiarize students with the vehicle

4、(2) before they (3) extensive and possibly dangerous actual flight training. Simulations also is useful for review and for familiarizing pilots with new (4) to existing craft.Two early flight simulators appeared in England within a decade after the first fight of Orville and Wilbur Wright. They were

5、 designed to enable pilots to stimulate simple aircraft (5) in three dimensions: nose up or down; left wing high and right low, or vice versa; and (6) to left or right. It took until 1929, however, for a truly effective simulator, the Link Trainer, to appear, devised by Edwin A. Link, a self-educate

6、d aviator and inventor from Binghamton, New York. (7), airplane instrumentation had been developed sufficiently to permit “blind” flying on instruments alone, but training pilots to do so involved (8) risk. Link built a model of an airplane cockpit equipped (9) instrument panel and controls that cou

7、ld realistically stimulate all the movements of an airplane. Pilots could use the device for instrument training, manipulating the controls (10) instrument readings so as to maintain straight and level flight or (11) climb or descent with no visual reference (12) any horizon except for the artificia

8、l one on the instrument panel. The trainer was modified (13) aircraft technology advanced. Commercial airlines began to use the Link Trainer for pilot training, and the US government began purchasing them in 1934, (14) thousands more as World War II (15).问题1选项A.forB.toC.withD.on问题2选项A.concerningB.co

9、ncernC.being concernedD.concerned问题3选项A.undertakeB.undergoC.underplayD.underuse问题4选项A.modelsB.modificationsC.modifiersD.modicum问题5选项A.manifestationsB.manipulationsC.manifestoesD.maneuvers问题6选项A.yawlingB.yawningC.yawingD.yawping问题7选项A.From then onB.From now onC.By nowD.By then问题8选项A.considerableB.con

10、siderateC.consideringD.considered问题9选项A.forB.inC.withD.on问题10选项A.On the part ofB.On the basis ofC.On the track ofD.On the verge of问题11选项A.controlB.controllableC.controlledD.controller问题12选项A.toB.forC.onD.in问题13选项A.as forB.as toC.asD.for问题14选项A.acquiringB.requiringC.sustainingD.retaining问题15选项A.reali

11、zedB.realizingC.approachingD.approached【答案】第1题:A第2题:D第3题:B第4题:B第5题:D第6题:C第7题:D第8题:A第9题:C第10题:B第11题:A第12题:A第13题:C第14题:A第15题:D【解析】1.【选项释义】A. for对于；因为 B. to给C. with和 D. on在之上【考查点】搭配。【解题思路】substitute作动词时，和for或者with搭配，substitute for sb./sth.表示“代替某人/某物”，substitute B with/by A表示“用A代替B”，空格处后面直接跟了actual figh

12、t training（实战训练），故填入for符合搭配，该题选择A项。【干扰项排除】B、D项不符合固定搭配；C项不符合句意。【句意】模拟的目的并不是要完全取代实战训练。2.【选项释义】A. concerning关于；涉及 B. concern担心；关心C. being concerned被关注 D. concerned相关的【考查点】非谓语动词。【解题思路】分析句子可知，空格处跟在名词vehicle的后面，是作vehicle的定语，concern是动词，不能直接跟在vehicle的后面，而vehicle和concern是被动关系，表示被涉及的，所以用concern的过去分词形式，故该题选择D项

13、。【干扰项排除】A项表示主动关系；B、C项是动词，不符合句子语法结构。【句意】模拟的目的不是要完全取代实战训练，而是要让学生彻底熟悉有关的工具。3.【选项释义】A. undertake承担；从事 B. undergo经历，经受C. underplay低调处理；降低的重要性 D. underuse未充分利用【考查点】搭配。【解题思路】根据宾语actual flight training（实际飞行训练）可知，空格处表示“经历”符合动宾搭配，其他三个选项都不符合句意，故该题选择B项。【干扰项排除】A、C、D项不符合动宾搭配。【句意】模拟的目的不是要完全替代实际的战斗训练，而是要在学生进行广泛的和可能

14、危险的实际飞行训练之前彻底熟悉相关的工具。4.【选项释义】A. models模型 B. modifications修改；改进C. modifiers修饰语 D. modicum少量，一点点【考查点】语义逻辑。【解题思路】根据existing和new可推知，new (34)是指在现有的飞机上进行的改进或修改，故该题选择B项符合句子逻辑。【干扰项排除】A、C、D项不符合句子语义逻辑。【句意】模拟也有助于检查和使飞行员熟悉对现有飞机的新改进。5.【选项释义】A. manifestations显示；表明 B. manipulations操纵；控制C. manifestoes宣言 D. maneuver

15、s机动动作；作战演习【考查点】句间逻辑。【解题思路】根据句子可知，冒号后的内容是对空格处进行的解释，根据冒号后的关键信息“机头向上或向下；机翼左高右低或相反”可知，这是对飞机进行动作操作，maneuver指操纵某物的动作，一般是用于作战目的，符合句子语境，故该题选择D项。【干扰项排除】A、C项不符合句意；B项多指需要熟练运用到手的操作，不符合语境。【句意】它们的设计是为了让飞行员在三维空间中模拟简单的飞机动作：机头向上或向下；机翼左高右低或相反。6.【选项释义】A. yawling双桅轻便帆船 B. yawning打哈欠C. yawing偏航 D. yawping叫喊；哭喊【考查点】联系上下文

16、。【解题思路】由to left or right（向左或向右），结合前文提到“在三维空间中模拟简单的飞机动作”可知，空格处表示“偏航”，故该题选择C项符合句意。【干扰项排除】A、B、D项都不符合句子语义逻辑。【句意】向左或向右偏航。7.【选项释义】A. From then on从那时起 B. From now on从现在开始C. By now到目前为止 D. By then到那时候【考查点】联系上下文。【解题思路】根据句子中的had been developed可知，“飞机上的仪器发展到足以允许盲人仅靠仪器飞行”这件事情是已经发生在过去，而上文说“直到1929年，一个真正有效的模拟器才被设计出

17、来”，说明这个模拟器设计的时间没有足以允许盲人飞行的仪器的发展时间长，也就是说到真正有效的模拟器设计出来的时候，飞机上的仪器已经发展到可以让盲人飞行的地步了，故该题选择D项符合上下文语义。【干扰项排除】A、B、C项不符合上下文语义。【句意】到那时，飞机上的仪器已经发展到足以允许“盲人”仅靠仪器飞行。8.【选项释义】A. considerable相当多（或大、重要等）的 B. considerate体谅的；体贴的C. considering考虑到；鉴于 D. considered经过深思熟虑的【考查点】联系上下文。【解题思路】由but可知，句子前后语义表示转折，前文说“飞机上的仪器发展到足以允许

18、盲人仅靠仪器飞行”，后文又提到“但是这样做的话会”，综合理解可推知involved (38) risk指的是“涉及到相当大的风险”，该题选择A项符合语义。【干扰项排除】B、C、D项不符合句子前后语义衔接。【句意】到那时，飞机的仪器已经发展到足以允许“盲人”仅靠仪器飞行，但训练飞行员这样做有相当大的风险。9.【选项释义】A. for对于；因为 B. in在里面C. with和 D. on在上面【考查点】搭配。【解题思路】equip作动词，常与with搭配，equip with表示“配备，装备”，故该题选择C项符合搭配。【干扰项排除】A、B、D项不和equip搭配使用。【句意】林克训练器建立了一个

19、飞机驾驶舱的模型，配备了仪表板和控制装置，可以真实地模拟飞机的所有动作。10.【选项释义】A. on the part of就而言 B. on the basis of根据；基于C. on the track of追踪 D. on the verge of濒临于；接近于【考查点】语义逻辑。【解题思路】根据manipulating the controls（操纵控制）和instrument readings（仪表读数）可知，操纵控制是基于仪表盘读数，所以空格处表示“基于”符合句意，故该题选择B项。【干扰项排除】A、C、D项不符合句子语义逻辑。【句意】飞行员可以使用该设备进行仪表训练，根据仪表读数

20、操纵控制，以保持直线和水平飞行。11.【选项释义】A. control指挥；控制 B. controllable可控制的C. controlled受控制的 D. controller控制器【考查点】搭配。【解题思路】分析句子可知，空格处前有or，表示空格处所填单词和maintain是并列动词，to是不定式，故空格处填入control的动词原形，该题选择A项。【干扰项排除】B、C、D项都不符合句子语法结构。【句意】飞行员可以使用该设备进行仪表训练，根据仪表读数操纵操纵装置，保持直线水平飞行或控制爬升或下降。12.【选项释义】A. to对；给 B. for因为；对于C. on在上面 D. in在里

21、面【考查点】搭配。【解题思路】根据空格前的reference可知，reference to sth.表示“参考某物”，故该题选择A项正确。【干扰项排除】B、C、D项均不和reference搭配。【句意】飞行员可以使用该设备进行仪表训练，根据仪表读数操纵操纵装置，保持直线水平飞行或控制爬升或下降，除仪表面板上的人工水平线外，无需任何地平线的视觉参考。13.【选项释义】A. as for关于；至于 B. as to至于；就而论C. as随着；当时 D. for因为；对于【考查点】联系上下文。【解题思路】上文提到飞行员可以用林克训练器进行多种操纵和控制，而飞机的仪器已经发展到足以允许“盲人”仅靠仪器

22、飞行，所以推断训练器随着飞机技术的进步而改进，空格处表示“随着”，故该题选择C项。【干扰项排除】A、B、D项不符合句子语义逻辑。【句意】训练器随着飞机技术的进步而改进。14.【选项释义】A. acquiring获得，得到 B. requiring要求C. sustaining维持；支撑 D. retaining保持；保留【考查点】联系上下文。【解题思路】空格后的thousands more是指“数千架训练器”，前文提到“美国政府在1934年就开始购买训练器”，后面又提到“随着二战又数千架训练器”可知，美国又购买了数千架，acquire表示“获得，得到”，放在句中符合上下文语义，故该题选择A项。

23、【干扰项排除】B、C、D项不符合上下文语义。【句意】随着二战又购买了数千架训练器。15.【选项释义】A. realized实现 B. realizing实现C. approaching接近 D. approached接近【考查点】语义逻辑。【解题思路】由as可知，as在句中作时间状语，表示是一件事情正在发生，另一件事也正在进行当中，但as从句中的动词一般用过去式，且按照句意“随着二战又购买了数千架训练器”可知，空格处表示“战争的临近”符合句意，故选择D项。【干扰项排除】A、B项不符合句意；C项不符合as时间状语从句的用法。【句意】随着第二次世界大战的临近，又购买了数千架训练器。3. 单选题A

24、comprehensive market system should be established to _ the flow of talent, funds and materials.问题1选项A.sufficeB.necessitateC.facilitateD.fabricate【答案】C【解析】【选项释义】A. suffice足够；足以 B. necessitate使成为必要C. facilitate促进；促使 D. fabricate编造；捏造【考查点】动词辨析。【解题思路】按照句意“应该建立一个全面的市场体系来_人才、资金和物资的流动”，根据空格后的单词flow可知，空格处表示

25、“促进”符合句意，故该题选择C项。【干扰项排除】A、B、D项都不符合句意。【句意】应该建立一个全面的市场体系来促进人才、资金和物资的流动。4. 单选题If she is stupid, shes _ pleasant to look at.问题1选项A.at any rateB.by chanceC.at a lossD.by the way【答案】A【解析】【选项释义】A. at any rate无论如何，至少 B. by chance偶然；意外地C. at a loss困惑不解；不知所措 D. by the way顺便问一下【考查点】词组辨析。【解题思路】按照句意“虽然她很笨，但_她长得很

26、好看”可知，空格处含有让步的意味，A项符合句意，故该题选择A项。【干扰项排除】B、C、D项都不符合句意。【句意】虽然她很笨，但至少她长得很好看。5. 单选题The tests show the earlier in life a person hears a sound the longer it is _.问题1选项A.retainedB.preservedC.remainedD.reserved【答案】A【解析】【选项释义】A. retained保留 B. preserved保护C. remained保持；停留 D. reserved保留；贮备【考查点】动词辨析。【解题思路】分析句子，it

27、指的是sound，根据longer可知，此处是说声音保留的时间越长，retain的牛津释义是to continue to hold（继续保持），该题选择A项符合句意。【干扰项排除】B项不符合句意；C项侧重保持一种状态或条件不变；D项侧重保留某种权利。【句意】测试表明，一个人在生活中听到声音的越早，它保留的时间就越长。6. 单选题Children and old people do not like having their daily _ upset.问题1选项A.habitB.routineC.practiceD.custom【答案】B【解析】【选项释义】A. habit习惯 B. rout

28、ine常规；惯例C. practice实践；实际行动 D. custom风俗；习俗【考查点】搭配。【解题思路】按照句意“孩子和老人不喜欢打乱他们的日常_”，daily routine是常见搭配，表示“日常生活，日常工作”，该题选择B项恰当。【干扰项排除】A项habit是可数名词，要加s；C项是指在一个特定的组织或情况下通常的或预期的做法；D项不符合句意。【句意】孩子和老人不喜欢打乱他们的日常生活。7. 不定项选择题There will eventually come a day when The New York Times ceases to publish stories on newsp

29、rint. Exactly when that day will be is a matter of debate. “Sometime in the future,” the papers publisher said back in 2010.Nostalgia for ink on paper and the rustle of pages aside, theres plenty of incentive to ditch print. The infrastructure required to make a physical newspaperprinting presses, d

30、elivery trucksisnt just expensive; its excessive at a time when online-only competitors dont have the same set of financial constraints. Readers are migrating away from print anyway. And though print ad sales still dwarf their online and mobile counterparts, revenue from print is still declining.Ove

31、rhead may be high and circulation lower, but rushing to eliminate its print edition would be a mistake, says BuzzFeed CEO Jonah Peretti.Peretti says the Times shouldnt waste time getting out of the print business, but only if they go about doing it the right way. “Figuring out a way to accelerate th

32、at transition would make sense for them,” he said, “but if you discontinue it, youre going to have your most loyal customers really upset with you.”Sometimes thats worth making a change anyway. Peretti gives the example of Netflix discontinuing its DVD-mailing service to focus on streaming. “It was

33、seen as a blunder,” he said. The move turned out to be foresighted. And if Peretti were in charge at the Times? “I wouldnt pick a year to end print,” he said. “I would raise prices and make it into more of a legacy product.”The most loyal customers would still get the product they favor, the idea go

34、es, and theyd feel like they were helping sustain the quality of something they believe in. “So if youre overpaying for print, you could feel like you were helping,” Peretti said. “Then increase it at a higher rate each year and essentially try to generate additional revenue.” In other words, if you

35、re going to make a print product, make it for the people who are already obsessed with it. Which may be what the Times is doing already. Getting the print edition seven days a week costs nearly $500 a yearmore than twice as much as a digital-only subscription.“Its a really hard thing to do and its a

36、 tremendous luxury that BuzzFeed doesnt have a legacy business,” Peretti remarked. “But were going to have questions like that where we have things were doing that dont make sense when the market changes and the world changes. In those situations, its better to be more aggressive than less aggressiv

37、e.”1. The New York Times is considering ending its print edition partly due to _.2. Peretti suggests that in face of the present situation, The Times should _.3. It can be inferred from paragraphs 5and 6 that a” legacy product” _.4. Peretti believes that in a changing world _.5. Which of the followi

38、ng would be the best title of the text?问题1选项A.the increasing online and salesB.the pressure from its investorsC.the complaints from its readersD.the high cost of operation问题2选项A.make strategic adjustmentsB.end the print sedition for goodC.seek new sources of leadershipD.aim for efficient management问

39、题3选项A.helps restore the glory of former timesB.is meant for the most loyal customersC.will have the cost of printing reducedD.expands the popularity of the paper问题4选项A.traditional luxuries can stay unaffectedB.cautiousness facilitates problem-solvingC.aggressiveness better meets challengesD.legacy b

40、usinesses are becoming out dated问题5选项A.Shift to Online Newspapers all at Once.B.Cherish the Newspapers Still in Your Hand.C.Keep Your Newspapers Forever in Fashion.D.Make Your Print Newspapers a Luxury Good.【答案】第1题:D第2题:A第3题:B第4题:C第5题:D【解析】1.【选项释义】1. The New York Times is considering ending its prin

41、t edition partly due to _. 1. 纽约时报正考虑终止印刷版，部分原因是_。A. the increasing online and sales A. 在线版和销量的增长B. the pressure from its investors B. 来自投资者的压力C. the complaints from its readers C. 读者的抱怨D. the high cost of operation D. 印刷成本高【考查点】细节事实题。【解题思路】首先定位首段首句“终有一天，纽约时报会停止在报纸上发表文章”可知，这是题干的同义表达，然后第二段第二句解释了其具体原因

42、“制造纸质报纸所需要的基础设施印刷机、送货卡车不仅昂贵；而且一个只提供在线服务的竞争对手却没有这样的经济上的限制，这是过分的”，从中可知，纽约时报正考虑终止印刷版，部分原因是因为印刷成本昂贵，D项“印刷成本高”符合题意。【干扰项排除】A项“在线版和销量的增长”、B项“来自投资者的压力”、C项“读者的抱怨”没有提到，这三项属于无中生有。2.【选项释义】2. Peretti suggests that in face of the present situation, The Times should _. 2. 佩雷蒂建议，面对目前的情况，纽约时报应该_。A. make strategic ad

43、justments A. 进行战略调整B. end the print sedition for good B. 永远停止印刷煽动C. seek new sources of leadership C. 寻找新的领导资源D. aim for efficient management D. 追求高效率的管理【考查点】细节事实题。【解题思路】根据关键词Peretti定位至第四段第一句“佩雷蒂说，纽约时报不应该浪费时间退出印刷版业务，但必须采取正确的方式”，理解可知，佩雷蒂建议纽约时报应该找到一种正确的方法来解决这件事情，所以A项“进行战略调整”符合题意。【干扰项排除】B项“永远停止印刷煽动”，原文

44、提到佩雷蒂认为不应该浪费时间退出印刷版业务，所以该项属于反向干扰；C项“寻找新的领导资源”和D项“追求高效率的管理”没有提到，这两项属于无中生有。3.【选项释义】3. It can be inferred from paragraphs 5and 6 that a” legacy product” _. 3. 从第5段和第6段可以推断“传统产品”_。A. helps restore the glory of former times A. 帮助恢复昔日的荣耀B. is meant for the most loyal customers B. 是针对最忠实的客户C. will have the

45、 cost of printing reduced C. 印刷成本会降低D. expands the popularity of the paper D. 扩大报纸的受欢迎程度【考查点】推理判断题。【解题思路】首先定位第五段最后一句“我不会选择一年结束印刷业，我会提高价格，让它更像一款传统产品”可以看出，佩雷蒂认为不仅要提高传统产品的价格，还要将它变为一种可以传承的产物，接着第六段开头提到“最忠实的客户仍然会得到他们喜欢的产品，他们会觉得他们在帮助维持他们所相信的东西的质量”，然后提到如果每年增加一些比例，依旧可以创收，紧接着提到“如果你要做一个印刷产品，那就为那些已经对它着迷的人做吧”，综合

46、理解可知，对于最忠实的客户来说，如果把传统产品进行改造，那么对于他们来说这就是一件可以传承的东西，由此推断，“传统产品”是针对最忠实的客户，该题选择B项“是针对最忠实的客户”符合题意。【干扰项排除】A项“帮助恢复昔日的荣耀”和C项“印刷成本会降低”没有提到，该项属于无中生有；D项“扩大报纸的受欢迎程度”，“传统产品”针对的是忠实的客户，让这个产品变成可以传承的东西，并没有扩大受欢迎程度，该项属于曲解原文。4.【选项释义】4. Peretti believes that in a changing world _. 4. 佩雷蒂认为，在一个不断变化的世界，_。A. traditional lux

47、uries can stay unaffected A. 传统奢侈品不会受到影响B. cautiousness facilitates problem-solving B. 谨慎有助于解决问题C. aggressiveness better meets challenges C. 积极进取能更好地迎接挑战D. legacy businesses are becoming out dated D. 传统企业正在变得过时【考查点】细节事实题。【解题思路】根据原文末段最后两句“但我们会有这样的问题，当市场和世界变化时，我们正在做的事情没有意义。在这种情况下，积极进取总比不那么积极进取要好（its b

48、etter to be more aggressive than less aggressive）。”可知，佩雷蒂认为，在一个不断变化的世界，to be more aggressive（积极进取）才更好处理世界变化带来的挑战，C项“积极进取能更好地迎接挑战”符合题意。【干扰项排除】A项“传统奢侈品不会受到影响”表述过于绝对，该项属于曲解原文；B项“谨慎有助于解决问题”在佩雷蒂的观点中没有体现，相反他建议要有所改变，并且要采取正确的方式，该项属于反向干扰；D项“传统企业正在变得过时”中的legacy businesses（传统企业）没有在文中讨论，该项属于无中生有。5.【选项释义】5. Whic

49、h of the following would be the best title of the text? 5. 下面哪个选项是这篇文章最好的标题？A. Shift to Online Newspapers all at Once. A. 同时转向在线报纸。B. Cherish the Newspapers Still in Your Hand. B. 珍惜手中的报纸。C. Keep Your Newspapers Forever in Fashion. C. 让你的报纸永远时尚。D. Make Your Print Newspapers a Luxury Good. D. 让你的纸质报纸

50、成为奢侈品。【考查点】主旨大意题。【解题思路】首先定位文章首段首句“终有一天，纽约时报会停止在报纸上发表文章”，可知本文讨论的内容是纸质印刷，然后第二段解释了抛弃纸质印刷的理由，接着中间四段介绍了佩雷蒂对纽约时报所面临的挑战进行的战略调整，即让纸质报纸成为legacy products（传统产品），之后，最后一段用佩雷蒂的话总结了当世界变化时，人们应该积极进取的迎接挑战；综上所述可知，这篇文章围绕的中心词就是print newspaper（纸质报纸），所以D项“让你的纸质报纸成为奢侈品”符合题意。【干扰项排除】A项“同时转向在线报纸”中的online newspaper只是文中提到的一个面临的

51、挑战，不足以引领全文，该项属于以偏概全；B项“珍惜手中的报纸”和C项“让你的报纸永远时尚”中的newspaper范围过大，本文的关键词是print newspaper（纸质报纸），这两项属于曲解原文。8. 单选题Learning how to think critically, do research, communicate, and improve writing skill, is all in preparation for a _ college curriculum.问题1选项A.cautiousB.prestigiousC.variousD.rigorous【答案】D【解析】【选

52、项释义】A. cautious小心的；谨慎的 B. prestigious有威望的；声誉高的C. various各种不同的；各种各样的 D. rigorous谨慎的；细致的【考查点】形容词辨析。【解题思路】按照句意“学习如何批判性地思考、做研究、交流和提高写作技巧，这些都是为一门_大学课程做准备”可知，学习思考、研究、交流和写作技巧都是作为一门严谨的大学课程所必备的，所以空格处表示“严谨的，严格的”符合句意，故该题选择D项。【干扰项排除】A、B、C项不符合句意。【句意】学习如何批判性地思考、做研究、交流和提高写作技巧，这些都是为一门严格的大学课程做准备。9. 不定项选择题As Gilbert

53、White, Darwin, and others observed long ago, all species appear to have the innate capacity to increase their numbers from generation to generation. The task for ecologists is to untangle the environmental and biological factors that hold this intrinsic capacity for population growth in check over t

54、he long run. The great variety of dynamic behaviors exhibited by different population makes this task more difficult: some populations remain roughly constant from year to year; others exhibit regular cycles of abundance and scarcity; still others vary wildly, with outbreaks and crashes that are in

55、some cases plainly correlated with the weather, and in other cases not.To impose some order on this kaleidoscope of patterns, one school of thought proposes dividing populations into two groups. These ecologists posit that the relatively steady populations have density-dependent growth parameters; t

56、hat is, rates of birth, death, and migration which depend strongly on population density. The highly varying populations have density-independent growth parameters, with vital rates buffeted by environmental events; these rates fluctuate in a way that is wholly independent of population density.This

57、 dichotomy has its uses, but it can cause problems if taken too literally. For one thing, no population can be driven entirely by density-independent factors all the time. No matter how severely or unpredictably birth, death, and migration rates may be fluctuating around their long-term averages, if

58、 there were no density-dependent effects, the population would, in the long run, either increase or decrease without bound (barring a miracle by which gains and losses canceled exactly). Put another way, it may be that on average 99 percent of all deaths in a population arise from density-independen

59、t causes, and only one percent from factors varying with density. The factors making up the one percent may seem unimportant, and their cause may be correspondingly hard to determine. Yet, whether recognized or not, they will usually determine the long-term average population density.In order to und

60、erstand the nature of the ecologists investigation, we may think of the density-dependent effects on growth parameters as the signal ecologists are trying to isolate and interpret, one that tends to make the population increase from relatively low values or decrease from relatively high ones, while

61、the density-independent effects act to produce noise in the population dynamics. For populations that remain relatively constant, or that oscillate around repeated cycles, the signal can be fairly easily characterized and its effects described, even though the causative biological mechanism may remain unknown. For irregularly fluctuating populations, we are likely to have too few observations to have any hope of extracting the signal from the overwhelming noise. But it now seems clear that all populations are regulated by a mixt