阐述结构（Expository Structure）是托福阅读中常见的段落组织形式，其核心是通过解释、举例、对比等方式展开论述。阐述结构通常具有清晰的逻辑顺序，从引入主题到展开细节，再到总结或强化观点，整个段落呈现出一种线性推进的特征。我们可以拆解为
Topic Sentence+Detail/Explanation+Example
Topic Sentence 主旨句：也可记为Argument观点句，表达段落的主旨，即本段想要表达的核心内容是什么。Detail/Explanation讲道理：展开细节，或是解释说明为何能得到本段的TS。
Example 摆事实：包含数据、例证、专家观点和引用。
常见表达-such as, like, for example/instance, specifically
在分辨阐述结构时，除了扫描是否有举例相关的逻辑词以外，我们还可以通过识别主旨句的方式达到。
辨别方法——识别主旨句（Topic Sentence）
阐述结构的段落通常会有一个明确的中心句，中心句是段落的核心观点，后续内容都是围绕它展开的。
常见位置：
1）句首-开篇点明；
2）句末-归纳总结；
3）第二句-出现在首句为问句或过渡句之后，抑或是陈述了一些现象或背景后的核心观点。
语言特征：
1）抽象或概括性的语言，而非具体的细节；
2）明确的主题词；
例如在children and advertising这篇文章中，段落的主旨句均包含主题词advertising和技巧technique的同义替换词。
General concern about misleading tactics that advertisers employ is centered on the use of exaggeration主旨句-新概念（预测后文将解释何为exaggeration并举例）. Consumer protection groups and parents believe that children are largely ill-equipped to recognize such techniques and that often exaggeration is used at the expense of product information. Claims such as "the best" or "better than" can be subjective and misleading; even adults may be unsure as to their meaning. They represent the advertiser's opinions about the qualities of their products or brand and, as a consequence, are difficult to verify. Advertisers sometimes offset or counterbalance an exaggerated claim with a disclaimer【解释】. 【举例】For example, the claim that breakfast cereal has a health benefit may be accompanied by the disclaimer "when part of a nutritionally balanced breakfast."
主旨句：广告商使用的夸大手法exaggeration是公众对其误导性策略的主要关注点
Explanation/Detail：儿童很难识别、以牺牲产品真实信息为代价，并给出了夸大表述的具体体现，如the best, better than
Example：breakfast cereal
阅读时理解阐述结构可以帮助我们迅速梳理出段落的重点信息-主旨句&细节/解释，例子是为了主旨句服务的，当我们已经理解了阐释的内容，举例内容可以略读，节约时间。
注意：
阐述结构并不意味着要严格按照TS+D+Example的结构呈现，有的段落没有Example只有details或explanation，有的段落则会将explanation和example混合在一起，这时就需要读明白例子的内容。例如：
The city of Venice, built on saltwater marshes and crisscrosses by canal, experienced problems with its water supply for most of its history【主旨句】. One fifteenth-century French traveler noted that “in a city in which the inhabitants are in water up to their mouths, they often go thirsty【引用】.” How was the community to solve this important problem?
这一简短段落是Water Supply in Venice中的首段，正好反应了TS+example的结构。
主旨句：威尼斯城长期面临水供应问题
Example：引用法国旅行者的话“在水里却常常口渴”，利用这种反差，突出问题的核心——尽管威尼斯被水环绕，但居民却缺乏可饮用的淡水。
The rising standard of living and the spread of standardized consumer goods also worked to level European society【主旨句】, as the percent of income spent on food and drink declined substantially. For example, the European automotive industry expanded phenomenally after lagging far behind the United States since the 1920s. In 1948 there were only 5 million cars in Western Europe, but in 1965 there were 44 million. Car ownership was democratized and came within the range of better-paid workers. Europeans took great pleasure in the products of the gadget revolution as well. Like Americans, Europeans filled their houses and apartments with washing machines, vacuum cleaners, refrigerators, dishwashers, radios, televisions, and stereos. The purchase of consumer goods was greatly facilitated by installment purchasing, which allowed people to buy on credit. With the expansion of social security safeguards, reducing the need to accumulate savings for hard times, ordinary people were increasingly willing to take on debt.
主旨句：生活水平的提高和标准化消费品的普及使得欧洲社会更加平等。
细节&举例：汽车工业的发展、家电产品的普及
阐述结构也常存在于并列结构、转折结构的分观点阐述中，即，段落整体是并列or转折，局部是阐述，如果同学们能够准确掌握阐述结构，那么这样的复杂结构就不在话下了。
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