GMAT真題閱讀—重力異常

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GMAT真題閱讀—重力異常

　　GMAT考試是現在很多人的熱門選擇，也是很多考試選擇的必須具備的考試項目。下面是yjbys網小編提供給大家關于GMAT真題閱讀—重力異常，希望對大家的備考有所幫助。

GMAT真題閱讀—重力異常

　　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.

　　當一個大型物體撞擊一顆行星或者衛星時，會出現物質噴射，所以行星上會出現坑和質量的虧損。這種虧損表現為重力的異常：被噴射出去從而形成坑的物質的移除導致了一個區域的重力略低于其周邊區域。所以有人會預期所有月球表面的多重環形沖擊盆地都會顯示負的重力異常，因為從本質上來說，他們都是月球表面的大坑。但是1994年由Clementine宇宙飛船手機的數據顯示許多這種月球盆地沒有異常的低重力并且一些甚至有異常的高重力。科學家們推測在月球歷史的早期，當大型沖擊體撞擊月球表面時，導致了成千上萬立方千米的地殼物質噴射，來自月球月幔的高密度物質迅速上涌覆蓋了沖擊體，補償了噴射出去的物質，所以在形成的盆地中沒有留下異常的低重力。然而在此之后，隨著月球變得越來越冷，越來越沒有彈性，來自大型沖擊體的回彈變得部分而不完整。所以在今天，這樣的重力不常將不會再出現：因為月球的表面太過寒冷和堅硬。01Question 1

　　According to the passage, the gravitational compensation in the highlighted text is caused by 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

　　Question 2

　　The passage suggests that if the scientists in the highlighted text 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

　　Question 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

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