标题: 新GRE阅读理解36套每日讨论--51（群178674184） [打印本页] 作者: 普渡哥 时间: 2011-10-28 03:03 标题: 新GRE阅读理解36套每日讨论--51（群178674184） Geologists have long known that the Earth‘s mantle is heterogeneous, but its spatial arrangement remains unresolved—is 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” (elements tending toward liquid rather than solid state) 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. (157 words)
10. According to the passage, it is believed that oceanic islands are formed from (A) the same material as mantle xenoliths (B) the same material as the midocean ridge system (C) volcanic rocks from the upper mantle (D) incompatible elements percolating up from the lower mantle (E) mantle plumes arising from the lower mantle
For the following question, consider each of the choices separately and select all that apply 11. It can be inferred from the passage that the sup- porters of the ―layered-mantle‖ theory believe which of the following? □A The volcanic rocks on oceanic islands are composed of material derived from the lower part of the mantle. □B The materials of which volcanic rocks on oceanic islands and midocean ridges are composed are typical of the layers from which they are thought to originate. □C The differences in composition between volcanic rocks on oceanic islands and the midocean ridges are a result of different concentrations of incompatible elements.
12. In the context of the passage, “unimaginatively” is closest in meaning to (A) pedestrian (B) controversial (C) unrealistic (D) novel (E) paradoxical作者: 普渡哥 时间: 2011-10-28 22:33
any answers?作者: sxldos 时间: 2011-10-28 22:57
10. E 11.AB 12.C作者: 普渡哥 时间: 2011-10-29 07:50
正确答案： 10. E 11. AB 12. A