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.
【新GRE逻辑阅读 每日一练29】相关文章:
最新
2016-03-01
2016-03-01
2016-03-01
2016-03-01
2016-03-01
2016-03-01