SAT阅读考试部分五篇文章中会考查两篇科学类的文章，有时候会出现一个科学类的双篇(如2016 年11 月亚太卷关于摩擦力的双篇难哭一众考生)。大家会普遍觉得科学类是一个比较容易的类别，备考过程中，很多同学会把重点放在历史类和文学类的文章上，可是你能做到科学类文章达到百分之九十以上的正确率吗?你能做到快速有效读完文章，保证充足的做题时间吗?做到以下几点，4 到5 分钟读懂科学类文章，从容完成题目不是梦!

背景知识

考试中遇到自己熟悉的话题，我们都会顿时觉得信心大增，元气满满，那么去哪里积累这些背景知识呢?托福TPO中的阅读和听力部分的文本给我们提供了大量的素材。同学们在刷TPO 的时候往往只关注了题目是否做的正确，笔记是否记到了重点，其实只要稍微多花一点点时间，就可以获取大量的背景知识信息。2016 年10 月亚太卷中关于Cambrian explosion 的文章与TPO 5 The Cambrian Explosion 简直如出一辙，因此请一定利用好TPO这一助攻神器。

没有真相，全是套路

作者是谁?他(她)有立场吗?

SAT 考试中选取的文章多为科普性质，或者讲述一个科学事实，或者陈述一个科学研究或者实验，作者的意图在于为我们提供信息，因此大部分文章的的语气是informative 而非argumentative，而这类文章通常也不会是科学家自己写的学术论文(我只是一个高中生，考科学家写的论文出题人是想难死我们?!)，只是对该领域相对熟悉的作者以客观的角度为我们陈述事实或呈现研究过程。

2016 年5 月亚太卷第43 题：

The passage is written from the point of view of a

A) consumer evaluating a variety of options.

B) scientist comparing competing research methods.

C) journalist enumerating changes in a field.

D) hobbyist explaining the capabilities of new technology.

可以很轻易判断出这是一位了解过该领域的journalist 对于solar panel 的发展过程的描述，而不是业余爱好者和科学家自己的角度。

利用好文章的开篇

科学研究类的文章一般有两种常见的开篇模式，一种是告知读者研究的目的，一种是陈述某个新的study 的结论。

OG Practice Test 3 第三篇文章的首段：

At field sites around the world, Ken Dial saw a pattern in how young pheasants, quail, tinamous, and other ground birds ran along behind their parents. "They jumped up like popcorn," he said, describing how they would flap their half-formed wings and take short hops into the air. So when a group of graduate students challenged him to come up with new data on the age-old ground-up-tree-down debate, he designed a project to see what clues might lie in how baby game birds learned to fly.

作者在首段末句陈述了Ken Dial 设计这个研究的目的在于观察小鸟如何学习飞行以更好的了解鸟类的祖先是如何获取飞行能力的，直接点明了Dial 所做研究的目的。

2017 年1 月北美卷第三篇首段：

Inflexible old salt becomes a softy in the nanoworld, stretching like taffy to more than twice its length, researchers report. The findings may lead to new approaches for making nanowiresthat could end up in solar cells or electronic circuits.The work also suggests that these ultra-tiny salt wires may already exist in sea spray and large underground salt deposits.

这个段落中，作者用很简单的三句话点名了研究者的发现—盐在纳米世界中会发生拉伸现象;这一发现的意义与应用—新的方法用来制造纳米线;这一现象在宏观世界中也存在。分析这三句话不难发现，研究的结论、意义和应用一应俱全，后文也是完全按照这个思路展开，文章结构清晰明了。

科学研究类文章的大致结构

作者在陈述某一科学研究或某一领域的研究现状及发展时会大致遵循一个基本的结构：

新研究的结论→过去研究的回顾与综述→研究的目的→研究方法或理论依据→实验设计→实验过程或现象观察→数据分析→观察结果或结论→形成理论→现实应用→研究存在的问题或对未来产生的深远的影响。

当然一篇文章不可能完全遵循以上的步骤，并且做到面面俱到，同学们可以在具体阅读过程中，结合文章实际情况，关注每个段落的首句并概况每个段落作者写作的意图来完成篇章阅读。

Khan Science Level 2:

Para.1: Nothing is more Australian than kangaroos. But these marsupials—along with a variety of others including the Tasmanian devil—have ancient roots in South America, a new study suggests.

Para.2: Exactly how these various marsupials, both living and extinct, are related has been murky.

Para.3: Some older studies suggested that marsupials first arose in Australia and that some marsupial lineages might have been split in two when these landmasses separated 80 million years ago.

Para.4: Maria Nilsson, Jürgen Schmitz, and colleagues present the first study to use the sequences of retroposed elements — a kind of "jumping gene" — to reconstruct marsupials' family tree.

Para.5: Retroposons use their own enzymatic machinery, or that of other retroposons, to copy their own RNA and create DNA copies of themselves.

Para.6: Also, the way they spread through the genome means they can occur in idiosyncratic patterns. So if different species share a few of the same nested retroposed elements, chances are overwhelming that they all got them from a longlost ancestor.

Para.7: In two marsupial genomes that were recently sequenced, Nilsson, Schmitz, and colleagues identified thousands of these nested retroposed elements...

Para.8: It hadn’t been clear which lineage of marsupials split off first, but the new study found this first branch gave rise to the Didelphimorphia lineage, which includes several species of opossums of South America. Further branches gave rise to other South American marsupials. All of today’s Australian marsupials appear to have branched off later, ...

Para.9: It’s still a bit of a mystery, Nilsson, Schmitz, and colleagues say, why the marsupial family tree sorted out so cleanly.

以上为可汗阅读科学类文章中一篇的摘录，根据每个段落的关键信号词我们可以很清楚的把握整个文章的思路。文章段作者首先给出了最近的一个研究的结论—有袋目动物的祖先出现在南美;第二三段阐述了令人困惑的问题并回顾了过去的研究;第四段到第六段描述了新研究的目的，即利用基因学的证据来研究有袋目动物的family tree，和研究手段(retroposed elements) 以及其独特性，这一独特性对研究构成了有力的支撑;第七段陈述了研究的过程;第八段为结论;最后一个段落指出了研究没能解决的问题。全文脉络清晰。

第八段我们保留了比较多的信息，这是因为这段涉及到整体研究的结论，这个部分是出题的重点，同学们不妨多花费一点时间仔细阅读并做好标记，其余的段落只要大致做出概括，方便细节题定位即可。

做题中的应用

对于结构做出的分析对于解题到底有什么意义呢?这是同学们普遍关注的问题，毕竟我们阅读文章最终的目的是要服务于题目的。我们来看一下这篇文章的典型题目。

What does the study of retroposed elements mainly indicate about marsupials in South America and Australia?

A) They have changed little over time.

B) They descended from a single species.

C) They are unrelated to other mammals.

D) They evolved earlier than believed.

该题考查研究的结论，如对结论记忆模糊，回结论段重新阅读。

The author uses the information in the paragraph 5 (lines 28-38) mainly to

A) stress the complexity of the marsupial genetic code.

B) point out inconsistencies in previous research.

C) explain the biological basis of the study.

D) suggest possible complications to the study.

该题考查第五段的作用，分析文章思路后发现第五段为retroposed elements 的特征，是整个研究的理论依据，直接选择C 选项。

最后希望同学们在备考过程中，选择有代表性文章做好精读，将以上技能灵活应用。

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