GRE閱讀文章的常見“主體結(jié)構(gòu)”介紹
GRE閱讀文章的常見“主體結(jié)構(gòu)”有三種：
1. 結(jié)論-解釋型(也叫論點-解釋型)
2. 新老觀點對比型
3. 現(xiàn)象解釋型(包含問題-解決方案型)
首先是“結(jié)論-解釋型”文章。這類文章在開始有一個判斷句，一般是文章的結(jié)論，也是文章的主題。這個判斷句的謂語部分通常包含系動詞(is, remain, prove, turn out, appear等)或情態(tài)動詞(can, may, should, must等)，而且含有表示態(tài)度的詞匯(如形容詞等)。例如，
Because of its accuracy in outlining the Earth's subsurface, the seismic-reflection method remains the most important tool in the search for petroleum reserves. In field practice, a subsurface is mapped by arranging a series of wave-train sources, such as small dynamite explosions, in a grid pattern…
文章首句指出：“由于‘地震反射法’(sr)在勾劃地球的地下層面這方面的準確性，該方法一直是探尋石油儲備的最重要的工具�！边@是一個判斷句，為結(jié)論。其中remains為系動詞，而most important為態(tài)度詞，表示作者對“地震反射法”持非常正面的評價。后文應(yīng)解釋“地震反射法”的具體過程。第二句話對解釋進行總的說明：“在實地作業(yè)中，通過將一系列波列源，諸如小規(guī)模炸藥爆炸，排列成一個網(wǎng)格模式，從而將地下層面標繪出來�！苯酉聛硎恰暗卣鸱瓷浞ā钡脑敿氝^程。
GRE閱讀文章的第二種常見結(jié)構(gòu)是“新老觀點對比型”。這類文章在開始提出老觀點，然后提出新觀點并進行論述。通常新觀點是文章的主題。老觀點出現(xiàn)的標志詞有：
1. 傳統(tǒng)觀點： has been, traditionally, until recently等
2. 大眾觀點：frequently, widely, many等
新觀點出現(xiàn)的標志詞有：however, recently, now等。
例如，
Traditionally, pollination by wind has been viewed as a reproductive process marked by random events in which the vagaries of the wind are compensated for by the generation of vast quantities of pollen, so that the ultimate production of new seeds is assured at the expense of producing much more pollen than is actually used.
However, a number of features that are characteristic of wind-pollinated plants reduce pollen waste….
文章首句指出：“傳統(tǒng)上，風媒授粉過程一直被視為是一個以隨機事件為標志的繁殖過程，其中風的不確定性通過產(chǎn)生大量花粉而得以補償，因此，新種子的最終繁殖得以保證，而此舉的代價是所需產(chǎn)生的花粉要遠遠超過實際的使用量�！庇傻谝粋�詞traditionally可知文章首句為老觀點(由于風的不確定性，風媒植物要產(chǎn)生大量花粉補償)，那么本文的結(jié)構(gòu)是“新老觀點對比型”。
第二段首句出現(xiàn)了GRE閱讀中的標志性轉(zhuǎn)折詞however，說明這句話就是新觀點：“但是，風媒植物所獨有的一系列特征可減少花粉浪費。”這說明風媒植物除了可以產(chǎn)生大量花粉加以補償?shù)南麡O策略之外，還可以通過一些積極機制減少花粉損失，不一定需要產(chǎn)生大量花粉。
GRE閱讀文章的第三種常見結(jié)構(gòu)是“現(xiàn)象解釋型”。文章開始提出一個現(xiàn)象，然后解釋現(xiàn)象。解釋是主題。有多個解釋時，作者一般對前面的解釋持負面評價，對最后的解釋持正面評價。提出現(xiàn)象時的.標志詞有：phenomenon, fact; problem, difficulty, puzzle, question等。例如，
What causes a helix in nature to appear with either a dextral ("right-handed,"or clockwise) twist or a sinistral ("left-handed," or counterclockwise') twist is one of the most intriguing puzzles in the science of form…What mechanisms, control handedness and keep left-handedness rare?
It would seem unlikely that evolution should discriminate against sinistral snails if sinistral and dextral snails are exact mirror images, for any disadvantage that a sinistral twist in itself could confer on its possessor is almost inconceivable. But left- and right-handed snails are not actually true mirror images of one another…
But this evolutionary mechanism combining dissymmetry, anatomy, and chance does not provide an adequate explanation of why right-handedness should have become predominant…
Here, the evolutionary theory must defer to a theory based on an explicit developmental mechanism that can favor either right- or left-handedness…Thus, the path to a solution to the puzzle of handedness in all snails appears to be as twisted as the helix itself.
是什么樣的原因致使自然界中的螺旋體呈現(xiàn)出右旋(“右向旋轉(zhuǎn)的”，或順時針的)或左旋(“左向旋轉(zhuǎn)的，”或反時針的)?這是形態(tài)科學中一個最引人入勝的不解之謎......究竟是一些什么樣的機制控制著旋轉(zhuǎn)方向，并使左旋的比例為數(shù)稀少呢?
假如左旋和右旋蝸牛呈完全一致的鏡像對稱的話，那么進化對左旋蝸牛不利，這近乎不太可能。幾乎無法想象左旋本身會給左旋者帶來任何不利之處。然而，左旋與右旋蝸牛彼此間實際上并不呈真正的鏡像對稱......
但是，這種結(jié)合不對稱、解剖學和偶然性的進化論機制并未提供一種充分的解釋，以說明蝸牛的右旋何以會成為主要的旋向......
于是，進化論必須讓位于支持右旋或左旋的明確的發(fā)育機制為基礎(chǔ)的理論......因此，解決所有蝸牛身上旋向之謎的道路似乎與這一螺旋體本身一樣曲折復(fù)雜。
上文在第一段最后提出一個問題：“究竟是一些什么樣的機制控制著旋轉(zhuǎn)方向，并使左旋的比例為數(shù)稀少呢?ァ閉飧鑫侍餼褪且桓魷窒螅郝菪體中左旋的比例少。有問題就有解答，有現(xiàn)象就有解釋。第二段從進化論的角度解釋這一現(xiàn)象。但是，GRE閱讀文章中一般對進化論的解釋持負面評價，所以需要尋找新的解釋。第三段否定了進化論的解釋。在末段，作者以發(fā)育機制(developmental mechanism)解釋“為何左旋少、右旋多”。
把握了文章的三種主體結(jié)構(gòu)以后，做文章后的許多題時易如反掌。以上述的“結(jié)論——解釋型”文章為例，如果熟悉文章的主體結(jié)構(gòu)，下面兩道題就很容易找到正確答案。
1. The passage is primarily concerned with
(A) describing an important technique
(B) discussing a new method
(C) investigating a controversial procedure
(D) announcing a significant discovery
(E) promoting a novel application
正確答案對應(yīng)文章首句的主題句。因此(A)為正確答案。
2. Which of the following best describes the organization of the passage?
(A) A method is criticized, and an alternative is suggested.
(B) An illustration is examined, and some errors are exposed.
(C) An assertion is made, and a procedure is outlined.
(D) A series of examples is presented, and a conclusion is drawn.
(E) A hypothesis is advanced, and supporting evidence is supplied.
本文的結(jié)構(gòu)是“結(jié)論—解釋型”，因此(C)為正確答案。
由此可見，把握文章的主體結(jié)構(gòu)，而不陷入文章詞句與細節(jié)的泥沼中，是一件快意的事情：文章讀得爽，題也做得爽。
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