新gre考试实施以来,参加了新版gre考试的考生都觉得阅读部分的题难度增加了,这主要是由于新gre考试逻辑阅读需要考生的逻辑反应一定要比以前更快,可能考生还是有点不习惯,或是没有准备充足。那么,接下来的几天,小编将给大家搜索整理一些新gre考试逻辑阅读的练习题,希望考生能从平日的练习中总结规律,找到解题技巧。
Geologists have long known that the Earths mantle is heterogeneous, but its spatial arrangement remains unresolvedis the mantle essentially layered or irregu-larly heterogeneous? The best evidence for the layered-mantle thesis is the well-established fact that volcanic rocks found on oceanic islands, islands believed to result from mantle plumes arising from the lower mantle, are composed of material fundamentally different from that of the midocean ridge system, whose source, most geologists contend, is the upper mantle. Some geologists, however, on the basis of obser-vations concerning mantle xenoliths, argue that the mantle is not layered, but that heterogeneity is created by fluids rich in incompatible elements percolating upward and transforming portions of the upper mantle irregularly, according to the vagaries of the fluids pathways. We believe, perhaps unimaginatively, that this debate can be resolved through further study, and that the under explored midocean ridge system is the key.获得更多gre考试咨询点击进入免费咨询顾问或联系QQ客服:800004500
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