托福阅读文章结构形式&阅读技巧

我们如果想取得托福阅读高分，很多情况下需要有一个宏观的角度来看文章结构。宏观的结构指的是文章是如何分布的，大致分为主旨结构和内容结构。拿到一篇文章我们主要先看文章的结构和主旨。而托福阅读常见的五种结构形式有：

A. 分类结构
　　B. 时间发展结构
　　C. 比较对比结构
　　D. 问题解决方法结构
　　E. 因果结构

今天我们来看一下分类结构的文章是如何布局和怎样阅读。

THE ORIGINS OF CETACEANS

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1.It should be obvious that cetaceans-whales, porpoises, and dolphins-are mammals.
　　2.They breathe through lungs, not through gills, and give birth to live young.
　　3.Their streamlined bodies, the absence of hind legs, and the presence of a fluke1 and blowhole2 cannot disguise their affinities with land dwelling mammals.
　　4.However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision what the first whales looked like.
　　5.Extinct but already fully marine cetaceans are known from the fossil record.
　　6.How was the gap between a walking mammal and a swimming whale bridged?
　　7.Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans.

文章第一句话讲明了cetaceans这种动物有哪些，同学们在阅读中如果遇到举例里面不认识的单词可以跳过，认识其中一个就可以了。第二句和第三句都在具体说明这些cetaceans有哪些特点。第四句说明这种动物很难辨别初期是长得怎么样的，只有从化石中获得信息。最后一句话提出一个问题：为了解决这个问题科学家就展开调查研究了。根据文章第一段，我们就知道了接下来的段落都会围绕如何去解决这个问题而展开。托福阅读中很多文章都是在段落第一段就提出一个问题，之后围绕这个问题去解决。

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Very exciting discoveries have finally allowed scientists to reconstruct the most likely origins of cetaceans. In 1979, a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale. The fossil was officially named Pakicetus in honor of the country where the discovery was made. Pakicetus was found embedded in rocks formed from river deposits that were 52 million years old. The river that formed these deposits was actually not far from an ancient ocean known as the Tethys Sea.

文章第二段第一句就是承上启下作用，我们也可以发现接下来的段落中都在讲Pakistan这个化石的细节信息。第一句在讲一个小组找到了P这个化石证明是证明和最古老的鲸鱼化石有关，并且在哪里发现的。

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The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales. Pakicetus probably detected sound through the ear opening as in land mammals.

The skull also lacks a blowhole, another cetacean adaptation for diving. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and cetaceans. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably bred and gave birth on land.

这段在任然在介绍Pakicetus的特点以及在倒数第三句开始讲和mammal之间的联系

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Another major discovery was made in Egypt in 1989. Several skeletons of another early whale, Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert. This whale lived around 40 million years ago, 12 million years after Pakicetus.

Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes. Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.

这段出现了一个新的化石B，具体讲述了B的特点以及和mammal之间的关联

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An even more exciting find was reported in 1994, also from Pakistan. The now extinct whale Ambulocetusnatans ("the walking whale that swam") lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus. The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea.

The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans. The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion. It was undoubtedly a whale that linked life on land with life at sea

这段讲了发现一个A的化石，具体介绍了A的特点和mammal之间的关系

总结：所以根据上文所有段落的介绍，我们平时在看文章的时候要注意下文章是按照什么结构来分的。如果掌握了文章结构，在找具体的信息和做题的时候就会心里有数，尤其是对做最后的文章主旨选择题和表格题会有很大帮助，否则大部分同学做最后一题的时候还是按照之前的印象半蒙半猜来做的。而且对于做细节信息相关的题目也会更有把握。

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