OG 2018阅读新题解析-《小行星碰撞》

OG2018阅读新题解析《小行星碰撞》When asteroids collide,some collisions cause an asteroid to spin faster;others slow it down.If asteroids are all monoliths---single rocks---undergoing random collisions,a graph of their rotation rates should show a bell-shaped distribution 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,because any loose aggregate spinning faster than once every few hours(depending on the asteroid's bulk density)would fly apart.Researchers have discovered that all but five observed asteroids obey a strict limit on rate of rotation.The exceptions are all smaller than200 meters in diameter,with an abrupt cutoff for asteroids larger than that.The evident conclusion---that asteroids larger than200meters 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 their mutual escape velocity.Over several hours,gravity will reassemble all but the fastest pieces into a rubble pile.Because collisions among asteroids are relatively frequent,most large bodies have already suffered this fate.Conversely,most small asteroids should be monolithic,because impact fragments easily escape their feeble gravity.1.The passage implies which of the following about the five asteroids mentioned?(highlight)A.Their rotation rates are approximately the same.B.They have undergone approximately the same number of collisions.C.They are monoliths.D.They are composed of fragments that have escaped the gravity of larger asteroids.E.They were detected only recently.2.The discovery of which of the following would call into question the conclusion mentioned?(highlight)A.An asteroid100meters in diameter rotating at a rate of once per weekB.An asteroid150meters in diameter rotating at a rate of20times perC.An asteroid250meters in diameter rotating at a rate of once per weekD.An asteroid500meters in diameter rotating at a rate of once per hourE.An asteroid1,000meters in diameter rotating at a rate of once every24hours3.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.B.Small asteroids will be monoliths.C.Small asteroids will collide with other asteroids very rarely.D.Most small asteroids will have very fast rotation rates.E.Almost no small asteroids will have very slow rotation rates.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 timeB.The speed with which impact fragments reassemble when they do not escape an asteroid's gravitational attraction after a collisionC.The frequency with which collisions among asteroids occurD.The rotation rates of asteroids smaller than200meters in diameterE.The tendency for large asteroids to persist after collisions原文解析：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 than200meters in diameter,with an abrupt cutoff for asteroids larger than that.The evident conclusion---that asteroids larger than200meters 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 velocity./Over 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fragmentsE.They were detect ed 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。