Automation refers to the introduction of electronic control and automation operation of productive machinery. It reduces the human factors, mental and physical, in production, and is designed to make possible the manufacture of more goods with fewer workers. The development of automation in American industry has been called the "Second Industrial Revolution".
　　这一段文字使我们了解了 "automation" 和 "Second Industrial Revolution" 两个概念，分别由 "refers to" 和 "been called" 引出。
　　常出现在定义法中的词语有：refer to, mean, call等。

8. 重复法(repetition)
　　句子的一部分反复出现在段落中，这就是重复法。它往往造成一种步步紧逼的气氛，使文章结构紧凑，有感染力。比如：
　　Since that time, which is far enough away from now, I have often thought that few people know what secrecy there is in the young, under terror. I was in mortal terror of the young man who wanted my heart and liver; I was in mortal terror of my interlocutor with the iron leg; I was in mortal terror of myself, from whom an awful promise had been extracted; --
　　该段中反复应用了I was in mortal terror of …我经常处于恐怖之中。
　　以上， 我们结合具体文章讨论了展开段落的几种方法。在实际写作中，我们往往不必拘泥于一种写作方法，而是将若干方法穿插在一起，使文章有声有色。

结尾段
　　我们知道文章的开头很重要，因为好的开头可以吸引读者、抓住读者的注意力。同样，文章的结尾也很重要，好的结尾会使读者对全文的中心思想留下深刻的印象，可以增添文章的效果和说服力，让人深思，回味无穷。确切地说，结尾的作用就是概括全文内容，进一步强调或肯定文章的中心思想，使读者加深印象；有时也用于展望未来，提出今后方向或令人深思的问题给读者留下回味和思考的余地。
　　但是，如何才能写好英文短文的结尾呢? 下面就介绍几种写结尾段最常用的方法：

　　1．重复中心思想: 回到文章开头阐明的中心思想或主题句上，达到再次肯定和强调的效果。
　　(例1)A sense of humor is really one of the keys to happiness. It gives zest to life to make it worth living.
　　(例2)With all these benefits, it is no wonder that sports and games have now become more popular with people than ever.

　　2．作出结论: 文章最后用几句话概括全文内容，并进一步肯定文章的中心思想或作者的观点。