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GAMT201708-og18阅读新题《小行星撞击》解

浏览次数:3236 日期:2017-09-05 17:33:59

When asteroids collide(本文话题), some collisions cause an asteroid to spin faster; others slow it down.(交代背景,与转速相关)If asteroids are all monoliths---single rocks---undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution(本层核心词) with statistical "tails" of very fast and very slow rotators. If asteroids are rubble piles, however, the tail representing the very fast rotators would be missing(本层核心词) because(因果关系连接词) any loose aggregate spinning faster than once every few hours (depending on the asteroid's bulk density) would fly apart. // Researchers have discovered(注意后面出现的观点,以及解释)that all but five observed asteroids obey a strict limit on rate of rotation. The exceptions are all smaller than 200 meters in diameter, with an abrupt cutoff for asteroids larger than that.

The evident conclusion---that asteroids larger than 200 meters across are multicomponent structures or rubble piles---agrees with recent computer modeling of collisions, which also finds a transition at that diameter. A collision can blast a large asteroid to bits, but after the collision, those bits will usually move slower than(注意一下这里的比较关系) their mutual escape velocityOver several hours, gravity will reassemble all but the fastest pieces into a rubble pile. Because(因果关系连接词)  collisions among asteroids are relatively frequent, most large bodies have already suffered this fate. Conversely, most small asteroids should be monolithic, because(因果关系连接词) impact fragments easily escape their feeble gravity.

 

逻辑简图:

第一段:

第一层:如果是整块石料,转率于钟型分布,有快有慢

第二层:如果是碎石堆,速度快的消失不见;除了5个以外,其它的行星转速都是有限制的

第二段:

第一层:证实了直径大于200的就是碎石堆;撞击之后,速度会减慢

第二层:引力不会聚集速度快的;大部分的小行星都是整块石料

 

1.The passage implies which of the following about the five asteroids mentioned? (highlight)

A Their rotation rates are approximately the same. 没有说它们的转速率几乎相同

B They have undergone approximately the same number of collisions.没有说它们经历了相同数量的撞击

C They are monoliths. 正确

D They are composed of fragments that have escaped the gravity of larger asteroids. 原文说是整块石料,不是fragments

E They were detected only recently. 没有说是最近才探测到的

 

解题思路:定位在第一段黄色高亮的部分。这道题目的解答需要从选项入手,结合全文内容来进行判断。原文说“除了5个之外,有速度限制“,那么这5个就是速度自由的,即可快可慢的monolith,选c

 

2.The discovery of which of the following would call into question the conclusion mentioned ?(highlight)

A An asteroid 100 meters in diameter rotating at a rate of once per week原文讨论的是直径大于200的,无关

B An asteroid 150 meters in diameter rotating at a rate of 20 times per hour原文讨论的是直径大于200的,无关

C An asteroid 250 meters in diameter rotating at a rate of once per week

一周一次,是慢的,加强

D An asteroid 500 meters in diameter rotating at a rate of once per hour

一小时一次,是快的,削弱,正确

E An asteroid 1, 000 meters in diameter rotating at a rate of once every 24hours         24小时一次,是慢的,加强

 

解题思路:注意题干当中的call into question,定位在第二段红色高亮的部分。原始逻辑是:”rubble piles不会特别快,所以直径大于200的是rubble piles”

 

3. According to the passage, which of the following is a prediction that is based on the strength of the gravitational attraction of small asteroids?

A Small asteroids will be few in number. 没有提到数量少

B Small asteroids will be monoliths. 最后一句话的同义转换,正确

C Small asteroids will collide with other asteroids very rarely. 没有提到与其它小行星的撞击频率

D Most small asteroids will have very fast rotation rates. 没说大部分的小行星是快的

E Almost no small asteroids will have very slow rotation rates. 没说小行星几乎都很快

 

解题思路:定位在第二段的第二层。

 

4. The author of the passage mentions "escape velocity" in order to help explain which of the following?

A The tendency for asteroids to become smaller rather than larger over time 没有说行星会变小而不是变大

B The speed with which impact fragments reassemble when they do not escape an asteroid's gravitational attraction after a collision 不是在说再聚合的速度

C The frequency with which collisions among asteroids occur 不是在说撞击的频率

D The rotation rates of asteroids smaller than 200 meters in diameter 不是为了说明直径小于200的行星转速

E The tendency for large asteroids to persist after collisions  正确

 

解题思路:定位在第二段绿色高亮的部分。原文说,速度变慢,后来被reassemble,即,为了说明大的小行星在撞击之后,如何保持,选e

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