在托福阅读中，学会提炼一个托福阅读文章的语言要素是十分重要的，本次百利天下小编以一篇原文为例，分析一下那些难解的语言要素。
托福阅读例子原文：
Geologists have long known that the Earth's mantle is heterogeneous， but its spatial arrangement remains unresolved—is the mantle essentially layered or irregularly 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 observations 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 underexplored midocean ridge system is the key.
1难词
spatial：a.1.空间的，太空的;2.存在(或者发生)于宇宙空间的
plume：n.1.羽状物2.柱，地柱
xenolith：俘虏岩
percolate：v.1.渗透2.扩散到，弥漫于
portions：n.一部分
2难句
难句1.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 mid-ocean ridge system， whose source，mostgeologists contend，is the upper mantle.
对于地幔分层论点来说，最好的证据乃这样一个确认的事实，即在那些海洋岛屿——这些岛屿据信是源于由下层地幔升上来的地幔柱状溶岩流(mantle plume)——上发现的火山岩石，是由与海洋中部山脊系统的物质根本不同的物质构成的，而这一海洋中部山脊系统的成因，大多数地质学家论辩道，为上部地幔。
难句类型：复杂修饰、插入语
解释：
本句前面的主干并不算难，即the evidence is the fact that，难就难在fact之后说明fact的同位语从句。此从句中既有大段插入语，又有从句，较为难读。同位语从句的主语是volcanic rocks，主语后面的found on oceanic islands是分词修饰volcanic rocks的;islands后面又有一个说明islands的同位语islands believed to result from mantle plumes arising from the lower mantle，此同位语实际起到一个分隔主谓的同位语的作用。其后是谓语动词are composed/of fundamentally different from that of the midocean ridge system， whose source， most geologists contend，is the upper mantle.
句中有一些专有词汇。如果抛开文章不说，单看这一个句子，则句首的layered mantle thesis就难以理解。但是如果读者能够读懂句子的大致意思，看到layered mantle thesisr最有力证据就是其材料fundamentally different from… the upper mantle，这应该可以推测出，既然不同于上层地幔，则这个理论一定是在说地幔有不同的层面。
3文章结构
Ts是文章的第一句，因此这一篇短文章是结论解释型。文章开始说出了地幔是heterogeneous，然后又指出了他的spatial arrangement remains unresolved，然后提出了两种理论，一是layyered-mantle thesis，另外一个是irregularly heterogeneous.然后分别对这两种理论进行describe.最后作者指出，We believe，perhaps unimaginatively，that this debate can be resolved through further study，and that the underexplored midocean ridge system is the key.
百利天下小编认为，考生在托福备考过程中，若要取得胜人一筹的高分，大家就需要在应试技巧的基础上，从难词、难句、文章结构等方面做分析吃透，才能真正提升自己对于托福阅读文章中语言要素的提炼能力，在考试中取得高分。
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