下面就是今天智课网小编给大家整理的2016年4月8日SAT阅读真题精选解析的内容,建议大家先自己试着做一下,然后能总结一些答题的方法,包括词汇的运用等。相信大家在努力备考之后总会取得一定的提高的。

  2016年4月8日SAT阅读题

  Four billion years ago, Earth's continents began taking shape. Scientists long held that this process unfolded gradually. It would have taken millions of years for granite, the primary component of the continental crust, to form in the mantle and migrate to the upper crust, they reasoned. But new research suggests that these events may have proceeded at rather a different pace. According to a report published in the journal Nature, the emergence of granite occurred by way of swift, dynamic and possibly catastrophic events lasting from 1,000 to 100,000 years.

  Geologist Alexander Cruden of the University of Toronto and his colleagues turned to experimental studies—melting rock samples, for example—to explore how granite magma forms and how fast it can move. Their results proved surprising. "In the past we thought that granite magma, which cools and crystallizes to form very large granite intrusions, moved up through kilometers of crust as large, solid blobs at rates of about a meter per year," Cruden says. "But we've found that magma actually has quite low viscosity and is relatively runny. Because it is runny, it is able to channel its way from the mantle and lower crust through fractures and cracks that are as small as one meter thick."

  According to this model, granite intrusions in Greenland or the Canadian Shield, depending on their size, would have taken only thousands of years to form, which is extraordinarily fast from a geological point of view, Cruden notes.

  The first paragraph of this passage serves primarily to ______________

  (A) introduce two competing explanations of a natural phenomenon.

  (B) establish the validity of evidence supporting a new scientific theory.

  (C) compare and contrast two perspectives on a recent discovery.

  (D) present a detailed timeline of advances in a field of study.

  解释:

  Choice A is the best answer. The first paragraph presents two different explanations for the formation of Earth's continents. The idea "long held" by scientists is that the formation "unfolded gradually" over "millions of years." The other idea, sparked by recent research, is that the formation occurred in a relatively "swift" period of "1,000 to 100,000 years."

  以上就是2016年4月8日的SAT阅读题,正确答案是A。

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