GMAT考试 6月5日更新GMAT阅读机经（五）.

　　GMAT考试已于6月5日正式更换题库了。以下是2012年6月的GMAT阅读机经更新，更新日期从6月5日起，澳际留学小编将为您提供最快，最新的GMAT阅读机经。澳际留学祝大家GMAT考试顺利!机经使用说明：1.*代表有考古。2.绿色代表考古标志，凡是未确认的都有灰色底色，没底色的就是已经确认了。3.紫色代表参考答案。4.红色代表重要提示。5.靛蓝代表参考文献。更多相关问题可咨询澳际留学在线专家，如果有任何意见和建议，也请联系我们。

12. Mass Extinctions聚群灭绝

　　Cases in which many species become extinct within a geologically short interval of time are called mass extinctions.There was one such event at the end of the Cretaceous period (around 70 million years ago). There was another, even larger, mass extinction at the end of the Permian period (around 250 million years ago). The Permian event has attracted much less attention than other mass extinctions because mostly unfamiliar species perished at that time.

　　The fossil record shows at least five mass extinctions in which many families of marine organisms died out. The rates of extinction happening today are as great as the rates during these mass extinctions. Many scientists have therore concluded that a sixthgreat mass extinction is currently in progress.

　　What could cause such high rates of extinction? There are several hypotheses, including warming or cooling of Earth, changes in seasonal fluctuations or ocean currents, and changing positions of the continents. Biological hypotheses include ecological changes brought about by the evolution of cooperation between insects and flowering plants or of bottom-feeding predators in the oceans. Some of the proposed mechanisms required a very bri period during which all extinctions suddenly took place; other mechanisms would be more likely to have taken place moregradually, over an extended period, or at different times on different continents. Some hypotheses failed to account for simultaneous extinctions on land and in the seas. Each mass extinction may have had a different cause. Evidence points to hunting by humans and habitat destruction as the likely causes for the current mass extinction.

　　American paleontologists David Raup and John Sepkoski, who have studied extinction rates in a number of fossil groups, suggest that episodes of increased extinction have recurred periodically, approximately every 26 million years since the mid-Cretaceous period. The late Cretaceous extinction of the dinosaurs and am monoids was just one of the moredrastic in a whole series of such recurrent extinction episodes. The possibility that mass extinctions may recur periodically has given rise to such hypotheses as that of a companion star with a long-period or bit dlecting other bodies from their normal orbits, making some of them fall to Earth asmeteors and causing widespread devastation upon impact.

　　Of the various hypotheses attempting to account for the late Cretaceous extinctions, the one that has attracted the most attention in recent years is the asteroid-impact hypothesis first suggested by Luis and Walter Alvarez. According to this hypothesis, Earth collided with an asteroid with an estimated diameter of 10 kilometers, or withseveral asteroids, the combined mass of which was comparable. The force of collision spewed large amounts of debris into the atmosphere, darkening the skies for several years bore the finer particles settled. The reduced levelof photosynthesis led to a massive decline in plant life of all kinds, and this caused massive starvation first of herbivores and subsequently of carnivores.The mass extinction would have occurred very suddenly under this hypothesis.

　　One interesting test of the Alvarez hypothesis is based on the presence of the rare-earth element iridium (Ir). Earth’s crust contains very little of this element, but most asteroids contain a lot more. Debris thrown into the atmosphere by an asteroid collision would presumably contain large amounts of iridium, and atmospheric currents would carry this material all over the globe. A search of sedimentary depositsthat span the boundary between the Cretaceous and Tertiary periods shows that there is a dramatic increase in the abundance of iridium brily and preciselyat this boundary. This iridium anomaly offers strong support for the Alvarez hypothesis even though no asteroid itself has ever been recovered.

　　13.墨西哥印第安人社区的研究

　　V1.第一段说某专家专门研究墨西哥裔印第安社区的发展，把墨西哥社区放在整个美国的背景里面研究，具体列举了一些方面。第二段说他跟其他人不一样，重点研究社区的中产阶级。第三段，该社区文化、组织架构、意识形态也难免会受到外部世界影响，在该社区可以避免外部世界受到的歧视。

　　问题：1.问了第三段作用。答案：第二段和第三段都是讲一个notion 这道题我在两个犹豫 一个说反映了他的书里的什么观点另一个说是sumarry of his view 还有一个选项问别人研究的都着重在哪些方面 我选的种族暴力什么的(定位第三段)

　　V2.第三篇讲一个什么家K专门研究墨西哥社区的发展，还是因为急，结果没有看清楚，第一段好像主要是说他研究墨西哥社区的发展的时候，把墨西哥社区放在整个美国的背景里面研究，具体列举了一些方面。第二段说他跟其他人不一样，重点研究社区的中产阶级，似乎说这些中产阶级劝其他人接受什么。第三段忘了

　　问题：1.有一个是说这个k跟其他研究的人不一样的地方是什么，但是我没有找到提到中产阶级的选项。在文章也找不到其他有提到其他人的地方，作了这么多真题，我觉得gmat的出题都是专业人士，考得又是你的能力，他们肯定会出一些隐含的文章的含义的题目，不是你用澳际的方法就可以解决的，所以澳际的东西不能全信，吸取一些技巧，但是阅读还是老老实实的看文章吧。

　　V3.一篇文章是关于美国墨西哥移民社区的文化认同的，先讲作者与4其他学者不同，把墨西哥社区的发展与整个社会的发展联系起来，再讲社区在面对歧视的时候还是会保持原有的文化认同，以团结起来。有一個人研究某個墨西哥社區,然後有提出他的研究關於應把該community容納到整個美國文化中討論,該研究特色是研究中產階級,還有biculture。

　　V4.第一段：一个名字很好听的学者研究墨西哥社区时和别的学者不同，别人都着眼种族斗争什么的(好像是这样，这里有题，说别的学者一般都在干什么，回原文找答案就好了)而这位仁兄把墨西哥融入到北美大环境下来看。第二段和第三段：分别讲这仁兄作品frame的两个方面，一个是中产阶级为重，二个是B开头的啥啥(惭愧，那词不认识，直接提的守字母没细看)要注意的是第三段有两道题，要细点看。

　　V5.休斯顿墨西哥社区的发展(社会科学—我的最弱项，并且这是我第三篇阅读，当时我比预计超时3分钟，为了追回时间，我只看了个结构，请谨慎参考。某学者专门研究Mexico community in Houston，说别人都着眼于人种、斗争之类的(有这么一道题，我选的就是有人种、肤色的那个)什么的，而这位学者把墨西哥社区的发展融入到整个美国社会的发展里来看问题。第二段上来就说这个学者的研究重点与别人不同，他研究的是中产阶级。然后就开始说他的研究怎么怎么样。(有一道题问，这个学者与别的学者的研究有什么不同，我把说这个学者的研究怎么怎么样的这句话取非进行的定位)。第三段说这个学者还有一个重点是bicultural，我没看明白他到底是想和外部世界沟通还是不想，但这里有两道题，我根据选项的动词的裹贬的感觉随便点了点。在这儿就不误导大家了。

　　V6.一个专家K专门研究Mexico Indian Community的发展。第一段主要是说他研究墨西哥社区的发展的时候，他把墨西哥社区放在host culture和整个美国发展的历史背景里面研究，与别的学者把两者割裂开不同。第二段说他重点研究社区的中产阶级，这些中产阶级劝其他人接受某些host culture(还是外部环境)的观点。第三段是他研究这个社区的biculturalism。该社区文化、组织架构、意识形态也难免会受到外部世界影响，在该社区可以避免外部世界受到的歧视。

以上就是6月5日更新的GMAT阅读机经，考生可以适当借鉴，并通过练习来掌握GMAT阅读的解题规律，从而在GMAT考试中发挥出更好的水平。关注此频道，还会有其他GMAT机经。

相关链接：

1.GMAT考试 6月5日更新GMAT阅读机经（六）

2.GMAT考试当天需要注意什么

3.GMAT阅读常见题型解题攻略：类比题