51. 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，most geologists contend，is the upper mantle. （5 -）
　　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。
　　意群训练：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，most geologists contend，is the upper mantle.
　　52. 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. （4+）
　　但是，某些地质学家，以对地幔捕虏岩体（xenolith）所作的观察为依据，指出地幔并非是分层排列的，相反，地幔的异质性是由那些富含“不相容成分”的流质构成的，这些成分趋向于流体而非固体的状态，自下而上渗透扩散，并依照这些流质流向的任意性，不规则地将上部地幔的某些部分予以改变。
　　难句类型：复杂修饰、插入语
　　解释：本句的主句中有一个长插入语however,on the basis of observations concerning mantle xenoliths,割裂了主谓，但句子的主要难度还是在that引导的宾语从句中，从句中有由but 所连接的两个句子，一起延续到句末。首选是rich in incompatible elements修饰fluids；后面又有一个同位语和一个分词结构，都是修饰incompatible elements的，最后还有一个状语来修饰那个分词结构，层层修饰，比较复杂。
　　意群训练：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.
　　53. fallois proposed that proust had tried to begin a novel in 1908, abandoned it for what was to be a long demonstration of saint-beuve's blindness to the real nature of great writing , found the essay giving rise to personal memories and fictional developments ,and allowed these to take over it a steadily developing novel. （5 -）
　　fallois认为，proust在1908年试图开始写一部小说，又为了写一部批判s-b的 伟大作品的真正本质的视而不见的长篇的证明而放弃了这部小说，其后又发现这一论文又勾起了其个人记忆及小说情节的萌生，使得后者取而代之形成了一部稳定展开的小说。
　　难句类型：复杂修饰、抽象词
　　解释：本句来自历来被gre考生尊称为所有gre文科文章中难度第一的普鲁斯特的追忆似水年华，这篇文章的难度远远高于现在计算机考试的题目。普鲁斯特是公认的意识流小说的先驱，据笔者推测，本文的原作者必定是研究普鲁斯特的大家，因此其文章必然带有思维的跳跃，、不连贯性、时空颠倒等意识流手法：经过ets的改编后，虽然可读性略有啬，然积重难返、无法救药，于是堕落成一篇流水帐文章。从本句的结构来看，也可以表现作者的这种叙事风格：本句从that引导的宾语从句开始，实际上是以普鲁斯特的意识流向为线索，以列举的方式描述其动机的变化，从一开始的写别的小说，其英文为prout had tried to…, abandoned…,found…,and allowed..。但是因为abandoned之后的状语for…的结构复杂、用词抽象，所以这个结构不太容易被看出来。blindness在此不是指真盲，而是指缺乏辨认能力difficult to discern, make out,or discover,视而不见。give rise to 这个词组的意思是引起，使发生。
　　意群训练：fallois proposed that proust had tried to begin a novel in 1908, abandoned it for what was to be a long demonstration of saint-beuve's blindness to the real nature of great writing , found the essay giving rise to personal memories and fictional developments ,and allowed these to take over in a steadily developing novel.
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