2007英语四级100篇精读荟萃中级篇(三十五)
文章作者 100test 发表时间 2008:01:04 13:23:38
来源 100Test.Com百考试题网
Passage Thirty-five (Exploration on the Origin of Continents)
The origin of continental nuclei has long been a puzzle. Theories advanced so far have generally failed to explain the first step in continent growth, or have been subject to serious objections. It is the purpose of this article to examine the possible role of the impact of large meteorites or asteroids in the production of continental nuclei. Unfortunately, the geological evolution of the Earth’s surface has had an obliterating effect on the original composition and structure of the continents to such an extent that further terrestrial investigations have small chance of arriving at an unambiguous answer to the question of continental origin. Paradoxically, clues to the origin and early history of the surface features of the Earth may be found on the Moon and planets, rather than on the Earth, because some of these bodies appear to have had a much less active geological history. As a result, re
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