【粤镀】遛粤粤镀机警整理（截止7月2日9:14,更新至70只狗）【结贴】

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evenqian

阅读54题，猜测考古:
When a large body strikes a planet or moon,material is ejected, thereby creating a hole in the planet and a local deficit of mass. This deficit shows up as a gravity anomaly: the removal of the material that has been ejected to make the hole results in an area of slightly lower gravity than surrounding areas.One would therefore expect that all of the large multi- ring impact basins on the surface of Earth's Moon would show such negative gravity anomalies, since they are, essentially, large holes in the lunar surface. Yet data collected in 1994 by the Clementine spacecraft show that many of these lunar basins have no anomalously low gravity and some even have anomalously high gravity. Scientists speculate that early in lunar history, when large impactors struck the Moon's surface, causing millions of cubic kilometers of crustal debris to be ejected, denser material from the Moon's mantle rose up beneath the impactors almost immediately, compensating for the ejected material and thus leaving no low gravity anomaly in the resulting basin. Later, however, as the Moon grew cooler and less elastic, rebound from large impactors would have been only partial and incomplete. Thus today such gravitational compensation probably would not occur: the outer layer of the Moon is too cold and stiff.

evenqian

GMAT阅读“重力异常”深度分析
作者：北美部GMAT项目组 周帆 李敏辉  来源：北京新东方学校  时间：2012-10-11
　　阅读建议：

　　1） 建议读者先按自己的节奏阅读文章并做完题目，再看文章分析及题目讲解。

　　文章及题目：

　　(This passage was excerpted from material published in 1996.)

　　When a large body strikes a planet or moon,material is ejected, thereby creating a hole in the planet and a local deficit of mass. This deficit shows up as a gravity anomaly: the removal of the material that has been ejected to make the hole results in an area of slightly lower gravity than surrounding areas.One would therefore expect that all of the large multi- ring impact basins on the surface of Earth's Moon would show such negative gravity anomalies, since they are, essentially, large holes in the lunar surface. Yet data collected in 1994 by the Clementine spacecraft show that many of these lunar basins have no anomalously low gravity and some even have anomalously high gravity. Scientists speculate that early in lunar history, when large impactors struck the Moon's surface, causing millions of cubic kilometers of crustal debris to be ejected, denser material from the Moon's mantle rose up beneath the impactors almost immediately, compensating for the ejected material and thus leaving no low gravity anomaly in the resulting basin. Later, however, as the Moon grew cooler and less elastic, rebound from large impactors would have been only partial and incomplete. Thus today such gravitational compensation probably would not occur: the outer layer of the Moon is too cold and stiff.

　　1. According to the passage, the gravitational compensation referred to the end of the paragraph is caused by which of the following?

　　(A) A deficit of mass resulting from the creation of a hole in the lunar surface

　　(B) The presence of material from the impactor in the debris created by its impact

　　(C) The gradual cooling and stiffening of the Moon's outer layer

　　(D) The ejection of massive amounts of debris from the Moon's crust

　　(E) The rapid upwelling of material from the lunar mantle

　　2. The passage suggests that if the scientists are correct in their speculations, the large multi-ring impact basins on the Moon with the most significant negative gravity anomalies probably

　　(A) Were not formed early in the Moon's history

　　(B) Were not formed by the massive ejection of crustal debris

　　(C) Are closely surrounded by other impact basins with anomalously low gravity

　　(D) Were created by the impact of multiple large impactors

　　(E) Were formed when the Moon was relatively elastic

　　3. Which of the following best describes the organization of the passage?

　　(A) An anomalous finding is cited, the data used to support that finding are analyzed, and the finding is modified.

　　(B) A theory about a phenomenon is introduced, data seeming to disprove that theory are analyzed, and the theory is rejected.

　　(C) A phenomenon is described, a finding relating to the phenomenon is discussed, and a possible explanation for that finding is offered.

　　(D) A debate among scientists regarding the explanation for a particular phenomenon is outlined, and one position in that debate is shown to be more persuasive.

　　(E)The observation of an astronomical event is described, and two schools of thought about the explanation for that event are discussed.

　　1. 文章初读：（只读各段首句）

　　第一段首句：

　　When a large body strikes a planet or moon， material is ejected， thereby creating a hole in the planet and a local deficit of mass.

　　翻译：当一个大型物体撞击一颗行星或者卫星时，会出现物质喷射，所以行星上会出现坑和质量的亏损。

　　2.  文章精读（精读各句，把握逻辑关系）

　　（标记重要逻辑关系词及态度评价词）

　　When a large body strikes a planet or moon,material is ejected, thereby creating a hole in the planet and a local deficit of mass. This deficit shows up as a gravity anomaly: the removal of the material that has been ejected to make the hole results in an area of slightly lower gravity than surrounding areas.One would therefore expect that all of the large multi- ring impact basins on the surface of Earth's Moon would show such negative gravity anomalies, since they are, essentially, large holes in the lunar surface. Yet data collected in 1994 by the Clementine spacecraft show that many of these lunar basins have no anomalously low gravity and some even have anomalously high gravity. Scientists speculate that early in lunar history, when large impactors struck the Moon's surface, causing millions of cubic kilometers of crustal debris to be ejected, denser material from the Moon's mantle rose up beneath the impactors almost immediately, compensating for the ejected material and thus leaving no low gravity anomaly in the resulting basin. Later, however, as the Moon grew cooler and less elastic, rebound from large impactors would have been only partial and incomplete. Thus today such gravitational compensation probably would not occur: the outer layer of the Moon is too cold and stiff.

　　翻译：

　　当一个大型物体撞击一颗行星或者卫星时，会出现物质喷射，所以行星上会出现坑和质量的亏损。这种亏损表现为重力的异常：被喷射出去从而形成坑的物质的移除导致了一个区域的重力略低于其周边区域。所以有人会预期所有月球表面的多重环形冲击盆地都会显示负的重力异常，因为从本质上来说，他们都是月球表面的大坑。但是1994年由Clementine宇宙飞船手机的数据显示许多这种月球盆地没有异常的低重力并且一些甚至有异常的高重力。科学家们推测在月球历史的早期，当大型冲击体撞击月球表面时，导致了成千上万立方千米的地壳物质喷射，来自月球月幔的高密度物质迅速上涌覆盖了冲击体，补偿了喷射出去的物质，所以在形成的盆地中没有留下异常的低重力。然而在此之后，随着月球变得越来越冷，越来越没有弹性，来自大型冲击体的回弹变得部分而不完整。所以在今天，这样的重力不常将不会再出现：因为月球的表面太过寒冷和坚硬。

　　读完文章后，可做如下笔记，整理各句大意及句间关系：

　　·strike→material eject→deficit of mass

　　·mass deficit→g anomaly

　　·g anomaly on Moon expected

　　·yet, many without

　　·scientists:

　　  ◇mantle compensation (no g anomaly)

　　  ◇later, however, no compensation (g anomaly)

　　3. 做题：

　　1. According to the passage, the gravitational compensation referred to the end of the paragraph is caused by which of the following?

　　(A) A deficit of mass resulting from the creation of a hole in the lunar surface

　　(B) The presence of material from the impactor in the debris created by its impact

　　(C) The gradual cooling and stiffening of the Moon's outer layer

　　(D) The ejection of massive amounts of debris from the Moon's crust

　　(E) The rapid upwelling of material from the lunar mantle

　　评：

　　1）直接细节题：正确答案为(E)。做直接细节题，首先要根据题干在原文中确定定位点，再根据原文内容进行选择与排除。正确答案往往是原文的同义改写。题目问“gravitational compensation”的原因，定位回原文第15至21行： …denser material from the Moon's mantle rose up beneath the impactors…可知是月幔上涌覆盖冲击体补充了质量缺失。E项属于对该句的同义改写。

　　2）错项分析：

　　(A)： 无关选项：重力补偿解决了重力亏损的问题，而不是由重力亏损导致。

　　(B)： 无中生有：文章并未提到冲击体的物质，文中涉及的物质的亏损与物质的喷射都是行星本身的现象，只不过这两种现象由冲击体撞击引起。

　　(C)： 无关选项：月球表层的冷却和变硬是重力补偿消失而非出现的原因。

　　(D)： 无关选项：月壳的物质喷射是出现异常低重力的原因而非出现重力补偿的原因。

　　2. The passage suggests that if the scientists are correct in their speculations, the large multi-ring impact basins on the Moon with the most significant negative gravity anomalies probably

　　(A) Were not formed early in the Moon's history

　　(B) Were not formed by the massive ejection of crustal debris

　　(C) Are closely surrounded by other impact basins with anomalously low gravity

　　(D) Were created by the impact of multiple large impactors

　　(E) Were formed when the Moon was relatively elastic

　　评：

　　1） 间接细节题：正确答案为(A)。注意题干中the most significant negative gravity的表达，揣摩命题人的出题意图。根据原文，我们知道冲击体撞击月球→撞击区域月球地壳物质喷射→喷射区域质量亏损并出现冲击盆地→喷射区域出现负的重力异常→月球早期月幔上涌，补偿重力→负的重力异常现象消失/→月球晚期月壳变冷变硬→月幔上涌受阻，重力补偿受阻→负的重力异常重新出现。所以月球上最显著的负的重力异常很可能只能出现在月球历史的早期。

　　2） 错项分析：

　　(B)： 与原文相反：原文明确说负的重力异常是由星球地壳物质喷射而成。

　　(C)： 无中生有：原文只说环形冲击盆地的重力略低于周围区域，不能推出周围区域也是负的重力异常区域。

　　(D)： 无中生有：环形冲击盆地是经冲击体撞击星球表面后，星球地壳喷射物质而成，并非直接由冲击体撞击而成。

　　(E)： 与原文相反：月球相对有弹性是在月球历史的早期，根据原文，月球早期因为有重力补偿现象，负的重力异常现象很可能不会出现。

　　3） 小技巧：

　　选项A和选项E正好的相反的意思，A项说不是在月球历史的早期形成，E项说在月球相对有弹性也就是在月球历史的早期形成。当选项中出现意思相对立的项时，   答案往往在其中产生。

　　3. Which of the following best describes the organization of the passage?

　　(A) An anomalous finding is cited, the data used to support that finding are analyzed, and the finding is modified.

　　(B) A theory about a phenomenon is introduced, data seeming to disprove that theory are analyzed, and the theory is rejected.

　　(C) A phenomenon is described, a finding relating to the phenomenon is discussed, and a possible explanation for that finding is offered.

　　(D) A debate among scientists regarding the explanation for a particular phenomenon is outlined, and one position in that debate is shown to be more persuasive.

　　(E)The observation of an astronomical event is described, and two schools of thought about the explanation for that event are discussed.

　　评：

　　1） 文章结构题：正确答案为（C）。这是一篇单一解释型文章，该类文章的结构往往呈现出三重态度，两次转折。开始部分一般针对对某种现象提出一个观点或理论，中间部分出现转折，举出反例看似证伪该观点理论，最后二次转折，通过分析和论证对反例给出合理解释，证实其不违背开始提出的理论。这类文章态度一般是：先正后负再正，最终达到了用提出的理论揭示了现象的目的。

　　2） 错项分析：

　　(A)： 第二部分的例子是用来证伪而不是支持理论

　　(B)： 最后理论被证实而不是被拒绝，

　　(D)(E)两项将文章分成两部分，明显与文章结构不符，单一解释性文章往往都分成三部分。

evakhuntoria

来晚了来晚了，赶快看起来，感谢

seraphjune

哇 希望能用到好用的阅读机经

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