在托福独立写作中很多考生都会碰到同一个问题：中间段除了分论点和例子就不知道写什么了，从而导致字数不达标，论点和例子之间没有过渡，连接牵强。那么下面就介绍一种高效好用并且简单掌握的扩充中间段的方法：因果链拓展。

所谓的因果链扩展就是讲道理，将中间段的主题句（topic sentence)进行进一步的解释，将隐含的逻辑关系解释清楚。写作过程中始终记好一个单词"why", 去解释为什么这个主题句成立。先拿生活中的例子来讲好了，有的同学迟到了，老师问其原因，他提出“天下雨了”作为自己的原因进行解释。听者似乎是明白了迟到的原因。但是仔细一想，为什么大家同处于一个天气环境，其他同学都没有迟到就他一个人迟到了呢。也就是说这个同学在进行原因解释的过程中还没有将其中隐含的因果关系解释清楚，还没有向听者解释好"why"这个单词。如果把欠缺的逻辑关系理清，就可以写成这样“因为天下雨了，路很滑，公交车开的很慢，公路很堵，我乘坐的68路车在最堵的干将路上停滞不动了，所以我迟到了。”

放到真实的托福写作过程中，因果链扩展是怎么得到运用的呢？Do you agree or disagree with the following statement? To achieve successful development of a country, a government should focus its budgets more on young children’s education rather than on universities. 有的同学也许脑子里马上想到一个理由，对儿童教育进行投资是最有效果的。论点完全正确，但是怎么将它说的有理有据呢？始终贯彻"why"这个单词，为什么对他们进行投资最有效果呢？因为孩子年龄小，处在关键时期-----这个阶段知识吸收比较快----教授的知识越好对他们将来的发展越有利----而这样的教学投资就是最具回报的。转化为英文就写成：Children aged three to five years old are quick learners in the new knowledge. Once imparted these new information, children will fast respond to them, which will be memorized in a short time and which will not be easily forgotten in the later years. The more advanced knowledge children learn, the better they will grow. That is, early education is the most effective one.

中间段扩展示范：

Do you agree or disagree with the following statement? Technology has made our children less creative than they were in the past. Use specific reasons and examples to support your answer.

①The benefits brought about by the expansion of software industry are enormous. ②In the past, children could only play chess, cards or other similar games with their friends. ③Now they can challenge other players via the Internet, professional or amateur, familiar or strange. ④Professional skills as well as the ability of critical and independent thinking are cultivated in the process. ⑤Games are not always the culprit of wasting children's time and they have their unique functions. ⑥Some on-line games, such as Counter Strike, by stimulating real life conditions, enable players to exercise various tactics in dealing with difficulties. ⑦In addition, under the help of Adobe Photoshop, children can easily create images with impact, forming stunning HDR images,removing noise, adding grain or creating vignettes with state-of-the-art photography tools, to name just few. ⑧These advanced softwares, to a great extent, enhance children's creative ability.

Do you agree or disagree with the following statement? Television advertisement directed toward young children (aged 2 to 5) should not be allowed.Use specific reasons and examples to support your answer.

①By watching these flowery advertisements, children will forge unnecessary purchasing desire. ②Advertisements always give an exaggerated account of products, with its fabulous visual effects, catchy promotion slogans and overwhelming celebrity endorsement. ③Who can resist Dextro Energy, when young children see their beloved carton figure Popeye gives up spinach for it? ④Who can resist M&M, when young children see colourful chocolate beans dance rhythmically in the screen? ⑤Who can resist Sour Marbels, when young children see giant beasts are choked by the sour candy? ⑥Who can resist Pringles chips, when young children's ears are echoed with crisp sound? ⑦Limited by their age, knowledge and experience, young children will easily fall victims to these advertisements, leading directly to their subsequent buying decisions or their thirst for buying.