16．1分类法
分类法（division and classification）是把一事物拆成几部分，表明这些部分与整体的关系。通常，作者以总类开头，然后把总类拆开，--列举部分或全部分类。
示范段落16－1
There are three basic kinds of materials that can be found in any good library．First，there are books on all subjects，both in English and in many other languages．These books are organized according to subject，title，and author in a central filing system called card catalog．Books can generally be checked out of the library and taken home for a period of two to four weeks．Second，there are reference materials，which include encyclopedias，dictionaries，bibliographies，atlases，etc．and which generally must be used in the library itself．Third，there are periodicals-magazines，news－papers，pamphlets-which are filed alphbetically in racks or which have been micro－filmed to conserve space．Like reference works，periodicals cannot usually be removed from the library．
16．2示范段落分析
主题句：There are three basic kinds of materials that can be foundin any good library．
分类词（Classifier）：kinds
列举词（Listing Signals）：first，second，third
分类（Categories）：1．books on all subjects
2．reference materials
3．periodicals
16．2关于如何写分类段落的建议
1）依据一个原则分类
把一事物分类后，要自始至终遵循同一分类原则。在示范段落16－1，分类原则是"the kinds of materials"。
2）所分类别必须互不包容
在示范段落16－1中，属于第一类的"books on all subjects"与属于第二类的"reference materials"界线分明．反之亦然。
3）分类必须完整
如果所分类别不完整，所作的分类则徒劳无益。如上例，所分三种"materials"应包括"all materials in a library"。
4）运用熟悉度方法排列
作者经常根据该读者对所分类别的熟悉程度排列顺序。通常先讨论读者最熟悉的，然后逐步讨论不熟悉的（关于熟悉度法见第19单元）。
5）使用分类词和列举符号
有经验的作者经常使用类词介绍概类，然后使用列举符号表明概类中的各分类。在示范段落16－1中，类词是"kind"，列举符号是"first，second，third"，下面是经常使用的类词：
kind，type，group，thought，way，class，part，element，factor，aspect，division，characteristic，subdivision，reasons，category，等等。
Exercise 16-1
Directions：Read the following paragraph，find out the topic sentence，the classifier，and the categories．
There are three fundamental human body types-endomorphic，mesomorphic，and ectomorphic．The extreme endomorph combines heavy fat distribution and lack of bony angularity with around face，short neck，wide hips，and heavy limbs．The extreme mesomorph has a solid chest，slender waist，long torso，and relatively short，powerful arms and legs．Extreme ectomorphs are characterized by their slender bodies，short trunks，long arms and legs，long narrow hands and feet，and lack of fat．
Topic Sentence：____________________________________________
Classifier：_____________
Categories：________________________________________________
Exercise 16－2
Directions：Divide the books college students often read into three kinds and describe them one by one．
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Exercise 16-3
Directions：Write a paragraph of division and catagory with the given topic sentence and details．
Topic sentence：A language is made up of many elements
Details：1．sounds 2．words 3．sentences
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