推展段落方法之九——因果法（Ⅰ）
17．1
因果法（cause and effect）段落通常回答“why？”的问题。大多数人认为在自己或别人生活中发生的事情必然事出有因，因此总要知道为什么会发生这样或那样的事情。原因（cause）指的是导致结果的发生在过去的事情，结果（effect）指的是已发生的事情将会产生的后果。
17．2结果法
解释一个原因（cause）的几个结果（effects）的段落，可能以下面两种顺序之一出现：或者以原因开头，接着指出一个一个结果，如下面示范段落17－1所示；或首先摆出结果，然后指出原因。
示范段落17－1
Many people are worried about what television has done to the generation of American children who have grown up watching it．For one thing，recent studies tend to show that TV stifles creative imagination．Some teachers feel that television has taken away the child's ability to form mental pictures in his own mind，resulting in children who cannot understand a simple story without visualillustrations．Secondly，too much TV too early tends to cause children to withdraw from real life experiences．Thus，they grow up to be passive spectators who can only respond to action，but not initiate it．The third area for concern is the serious complaint frequently made by elementary school teachers that children exhibit a low tolerance for the frustrations of learning．Because they have been conditioned to see all problems resolved in 30 or 60 minutes on TV，they are quickly discouraged by any activity that promises less than instant gratification．But perhaps the most serious result is the impact of television violence on children，who have come to regard it as an everyday thing．Not only does this increase their tolerance of violent behavior in others，but most authorities now concede that under certain conditions，some children will imitate anti－ social acts that they witness on television．
17．3示范段落分析
主题句：Many people are worried about what television has done to the generation of American children who have grown up watching it．
因果模式（cause and effect pattern）：
原因（cause）：television
结果（effects）：1．TV stifles creative imagination．
2．TV causes children to withdraw from real life experiences．
3．Children exhibit a low tolerance for the frustrations of learning．
4．Children have come to regard violence as an everyday thing．
17．4关于如何写因果法段落的建议
1）段落一开始就表明目的
在段落一开始就陈述你所关心的原因或结果是什么。例如，在示范段落17－1，主题句就把目的限定为分析“the effects of television on American children”。
2）选择主题要适中
选择太大的主题会给你带来麻烦。因此，记住要选择你可以驾驭的主题。例如：“effects of television”作为主题会太大，难以下笔。然而把它限制为“effects on American children”就容易多了（第18单元继续讨论因果法）。
