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(難) Passage 20: 关于文章的标： 帮助理解文章的逻辑框架，都是TS,或举例（为了说明观点） 帮助理解记忆文章内容：时间，地点，人物，书名，事件 语言现象：指代，比较，并列，对比，引号，冒号登，一般是出题点。 表示注意某人的观点 附评价（－） 正评价（＋）
After evidence was obtained
in the 1920’s that the universe is expanding, it became reasonable to ask:
will the universe continue to expand indefinitely, or is there enough mass in it for the
mutual attraction of its constituents to bring this expansion to a halt?(现象：宇宙扩张，引出问题：继续还是停止)
It can be calculated that the critical density of matter needed to brake the expansion and “close”（引号，表强调,出题点）the universe is equivalent to three hydrogen atoms per cubic meter.
But the (10) density of the observable universe—luminous matter in the form of galaxies—comes to only a fraction of this. If the expansion of the universe is to stop, there must be enough invisible matter in the universe to exceed the luminous matter in density (15) by a factor of roughly 70. Our contribution to the search
for this “missing matter”(引号表强调) has been to study the rotational velocity of galaxies at various distances from their center of rotation.（TS：对上段提出假设的研究）
It has been known(+)for some time that (20) outside the bright nucleus of a typical spiral galaxy luminosity falls off rapidly with distance from the center.
If luminosity were a true indicator of mass, most of the mass would be concentrated toward the center. Outside the nucleus the rotational (25) velocity would decrease geometrically with distance from the center, in conformity with Kepler’s law(假设)
Instead（转折，和假设不同）we have found that the rotational velocity in spiral galaxies
either remains constant with increasing distance from the center
or increases (30) slightly. This unexpected result indicates that the falloff in luminous mass with distance from the center is balanced by an increase in nonluminous mass. 2nd: 关于上段假设的研究，以前普遍的发现，研究的发现－和假设不同的结果，提出的结论。研究结果） Our contribution to the search, missing matter, study, it has been known for some time, If…, instead, unexpected result…
Our findings suggest that as much as 90 (40) percent of the mass of the universe is not radiating at any wavelength with enough intensity to be detected on the Earth. Such dark matter could be in the form of extremely dim stars of low mass, of large planets like Jupiter, or of black holes, (45) either small or massive. While it has not yet been determined whether this mass is sufficient to “close” the universe, some physicists consider
it significant that estimates are converging on the critical value（＋）. 3rd: 研究结果的结论。 Our finding suggest…,such…,while,….consider significant(+)
Questions 111-116 refer to the passage above. 111. The passage is primarily concerned with 結構題－research是中心詞 (A) defending a controversial approach (B) criticizing an accepted view (C) summarizing research findings (D) contrasting competing theories (E) describing an innovative technique 112. The authors’ study indicates that, in comparison with the outermost(離中心最遠的) regions of a typical spiral galaxy, the region just outside the nucleus can be characterized as having
（即核外的與離核最遠的做比較－搞清楚比較關係） 快速扫答案，知道再说速度和光亮度，马上可以定位第二段，重读。注意问题问得是just outside the nucleus的velocity and luminosity. 定位比较容易，但是我觉得句子不容易理解，我看了好久，看了OG才理清楚的（也可能不清楚，请各位提出意见），注意是实际情况，那么都出自于结论性的话语，而那一段写有很多关于veolocity和luminosity的叙述，特别在Kepler’s law部分，但是这部分不是出答案的地方，反正我开始是读不清楚。 关于luminosity: It has been known for some time that[outside the bright nucleus of a typical spiral galaxy ]luminosity
falls off [rapidly with distance from the center]. 前面是本段的主题：对于上一段提出的问题的研究贡献：离银河系旋转中心的旋转速度的研究。后面是对研究的假设。那么这句话it has been know for some time…是在做研究以前已经认可的。知道中间部分亮，越远越暗。在B D选答案。 关于velocity: Instead we have found that the rotational velocity in spiral galaxies either remains constant with increasing distance from the center or increases slightly. 速度要么随着距离的增加不变要么增加一点点。选D。 在把中间假设部分的句子读一下：If luminosity were a true indicator of mass, most of the mass would be concentrated toward the center. Outside the nucleus the rotational velocity would decrease geometrically with distance from the center, in conformity with Kepler’s law。如果发光度是mass的指示，大多数mss都将向中间靠拢。按照Kepler的定理：在核心以外的速度会随离中心距离的增加而下降。 (A) higher rotational velocity and higher luminosity (B) lower rotational velocity and higher luminosity (C) lower rotational velocity and lower luminosity (D) similar rotational velocity and higher luminosity (E) similar rotational velocity and similar luminosity 113. The passage suggests that the results of the authors’ study have changed their ideas about which of the following characteristics of spiral galaxies?逐条分析: I. II. III.关于作者的研究，定位在第二段。 I.
The relative luminosity of different regions II. The relative rotational velocity of different regions 和假设不同，改变的部分，选。 III. The relative distribution of matter in different regions (A) I only (B) II only (C) III only (D) II and III only (E)
I, II, and III 羅馬題類似EXCEPT題︰ I錯︰luminosity的理論並未改變－隨距離增加而降低 II對︰和假设不同，改变的部分，选。 III對︰第二段的结论：This unexpected result indicates that the falloff in luminous mass with distance from the center is balanced by an increase in nonluminous mass是关于distribution的叙述。选
114. The authors’ suggestion that “as much as 90 percent of the mass of the universe is not radiating at any wavelength with enough intensity to be detected on the Earth” (lines 39-42) would be most weakened if which of the following were discovered to be true? 逻辑题－削弱。题目引的这句话as much as 90 percent of the mass of the universe is not radiating at any wavelength with enough intensity to be detected on the Earth作为这道因果逻辑题的结论。是研究的结果。找到这话向对应的原因，即研究结果：This unexpected result indicates that the falloff in luminous mass with distance from the center is balanced by an increase in nonluminous mass，得出这个研究又是基于研究的产生：has been to study the rotational velocity of galaxies at various distances from their center of rotation这题其实OG解释很清楚。即反驳得到结论的前提来削弱。 如果看的时候能一眼看到结论中universe这个词，但是上一段明显是围绕旋转的galaxies来说的。看到A应该觉得像答案，其它又比较容易排除，可以选出A 看了OG觉得不难，其实我还是觉得挺难的。不知道哪位NN有更好的方法 (A) Spiral galaxies are less common than types of galaxies that contain little nonluminous matter.（質疑該研究的假設: Spiral galaxies不能代表所有galaxies）－削弱 (B) Luminous and nonluminous matter are composed of the same basic elements. (C) The bright nucleus of a typical spiral galaxy also contains some nonluminous matter (D) The density of the observable universe is greater than most previous estimates have suggested.(不能weaken－因 “But the (10) density of the observable universe—luminous matter in the form of galaxies—comes to only a fraction of this.”－close the university) (E) Some galaxies do not rotate or rotate too slowly for their rotational velocity to be measured.（some不能weaken－另外author are concerned only with measurable rotational velocity） 115. It can be inferred from information presented in the passage that if the density of the universe were equivalent to significantly less than three hydrogen atoms per cubic meter, which of the following would be true as a consequence? (A) Luminosity would be a true indicator of mass. (段落定位錯) (B) Different regions in spiral galaxies would rotate at the same velocity. (2nd) (C) The universe would continue to expand indefinitely. (D) The density of the invisible matter in the universe would have to be more than 70 times the density of the luminous matter.(=3的狀況) (E) More of the invisible matter in spiral galaxies would have to be located in their nuclei than in their outer regions.（段落定位錯） 可定位細節題－原句 “It can be calculated that the critical density of matter needed to brake the expansion and “close” the universe is equivalent to three hydrogen atoms per cubic meter. 116. The authors propose all of the following as possibly contributing to the “missing matter” in spiral galaxies EXCEPT 原句 “Such dark matter could be in the form of extremely dim stars of low mass, of large planets like Jupiter, or of black holes, (45) either small or massive.” (A) massive black holes (B) small black holes (C) small, dim stars (D) massive stars (E) large planets
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