新GRE逻辑阅读 每日一练29

　　编辑点评： GRE阅读考试的材料，非常强调逻辑的关系，所以逻辑要点是大家在解GRE阅读题的时候的关键，本文就为大家例举了这样一篇逻辑短文，供大家参考和练习。

　　随着GRE阅读考试的难度日益增加，大家需要有针对性地进行练习，本文为大家例举的就是逻辑短文的练习，文末还附有答案，供大家更好地练习。

　　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 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.

　　10. According to the passage, it is believed that oceanic islands are formed from

　　the same material as mantle xenoliths

　　the same material as the midocean ridge system

　　volcanic rocks from the upper mantle

　　incompatible elements percolating up from the lower mantle

　　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

　　pedestrian

　　controversial

　　unrealistic

　　novel

　　paradoxical

　　答案：10. E 11. AB 12. A

　　上文的题目大家答对了几题?大家不仅要多做题，更要善于总结，这样才会有针对性地提高。