在上一讲中，我们介绍了有效地找出段落主题句的重要性。那么具体怎样操作呢？
我们先来看一下主题句的特点：
² 内容：一般比较抽象概括
² 位置：一般出现在两个位置的可能性最大：每段话的开头和结尾。
通常而言，主题句就是一段话的第一句。后面的句子一般为支持性的细节，以解释、发展或是支持主题句所表现的主要论点。
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The recent string of corporate scandals provided a rude awakening to the importance of these internal checks. In the case of WorldCom, it was internal auditor Cynthia Cooper who blew the whistle on the company for inflating profits by $3.8 billion. She didn’t intend to be a hero, she said to Time magazine when it named her one of its Persons of the Year. She was just doing her job.
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Chief constables had disapproved of the use of league tables. They complained that they provoked unfair criticism because they did not compare like with like. Mr. Denham said the graphs were easier to comprehend than tables. “As people get familiar” with this type of graphical presentation they will realize it contains a lot of data that can be understood after an initial glance. “ The spidergrams are based on five indicators: reducing crime, investigation crime, public safety, deployment of resources and the view of a focus group of local citizens.
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有时候主题句也会出现在整段话的最后。这样的结构安排，通常出现在一个讨论困难的、不为大众所接受的话题或者文章的主要目的是为了说服读者接受某种结论的段落中。因为先把道理说清楚，那么读者就会比较容易接受新的观点和看法。
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If the wind becomes gusty after a period of calm, you should seek shelter. The sky needs careful watching too. Gradual darkening and “boiling” clouds should quicken your pace. Lightening and thunder are common enough storm indicators, but few people realize that the brightness of the lightening is not nearly as important as the number of lightning flashes. The signs of an oncoming storm are many, and a person’s life may depend on his ability to interpret them,
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主题句也可能在段落当中:
From one perspective, this huge customer base represents a hair-raising social liability. Surgical and hospital costs fro regular heart transplants run as high as $500,000. these procedures haven’t burdened the medical system so far – but only because the supply of transplantable hearts has been limited to about 2000 a year. Abiomed plans to price its heart between $75000 and $10000 initially, and with volume production, the price could fall as low as $10000. However, even at the lower price, artificial hearts are an issue that will lead into moral quicksands, says medical ethicist David Steinberg of the Lahey Clinic in Burlington, Mass. What happens, Steinberg muses, “if heart replacement – and intervention directly and visibly linked to who will live and who will die—becomes available only to those who can afford it?”
² 标志词：有些词汇对于我们正确判断一段话的主题是至关重要的。在雅思考试的文章中，主要有两类：强转折性的词、表示重要性结构的词和表示人物观点结论性的词。
那么这些标志词的具体特征和作用如何呢，且看下回分解。
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