20．1 混合方法（Mixed Patterns）
到目前为止，我们讨论了九种推展段落方法--1）事实数据法（facts and statistics）；2）叙述法（narration）；3）描述法（description）；4）过程分析法（process analysis）；5）定义法（definition）；6）举例法（examples）；7）比较对比法（comparison and contrast）；8）分类法（division and classification）；9）因果法（cause and effect）。我们还讨论了四种组织段落的方法：1）时间顺序法（time order）；2）空间顺序法（space order）；3）重要性顺序法（order of importance）；4）熟悉度顺序法（order of familiarity）。此外，我们还谈及一个好的段落的三个特征：1）完整性（completeness）；2）统一性（unity）；3）连贯性（coherence）。
我们在前面各单元的示范段落中已经发现，极少段落是仅用一种推展方法的。作者常常在段落中使用一种方法作为支配方法（dominant method），另外一种或数种作为辅助方法（supporting method）。
示范段落20-1
Man's knowledge of the past has sometimes been gained in odd ways．One of the oddest incidents occurred on January 16，1900．An angry workman broke a crocodile mummy into pieces．He wassurprised to find that the mummy had been wrapped in sheets of papyrus，the reed paper of ancient Egypt．And on the papyrus there was writing．
20．2示范段落分析
主题句：Man's knowledge of the past has sometimes been gained in odd ways．
组织段落顺序：Time order
支配推展方法：Example
辅助推展方法：Narration
示范段落20-2
There are two kinds of memory：short-term and long-term．Information stored in the long-term memory can be recalled at a later time when it is needed．The information may be kept for days or weeks．In contrast，information stored in the short-term memory is kept for only a few minutes，usually by repeating the in formation over and over．
20．3示范段落分析
主题句：There are two kinds of memory：short-term and long-term．
组织段落方法：Order of Familiarity
支配推展方法：Division and Classification
辅助推展方法：Description，Contrast
Exercise 20-1
Directions：Write a paragraph on population increase，using cause and effect as the dominant method，and examples，facts or statistics as the supporting methods．
Why has the world population been increasing so rapidly in the last decades？_____________________________________________________
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Exercise 20-2
Directions：Write a paragraph on why you chose your specialty，combining the various methods you have learned．
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Exercise 20-3
Directions：Write a paragraph about whether weekend homework should be abolished．
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Exercise 20-4
Directions：Write a paragraph about your favourite season．
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