25.1 Definition and Classification(定義與分類)
A writer often employs more than one method of development in an order to make it easier or clearer for the reader，the author may，for instance，decide to classify objects，events or terms by retaining a few classes rather than many specific tionally，he may need to define the lables he uses in classifying the subject，especially if the lables are not widely known or are abstract.
在進行定義或分類寫作時需注意：1)在進行詮釋(定義)時，一定要具體、確切;2)分類時要周密，標準必須對應劃一，不能交錯重疊。
Model Essay 25-1
Nowadays，more and more people have books in their homes，but few of them really ownthe Professor Adlers opinion，there are three kinds of book first kind of owners have all the standard sets and best-sellers-books that are sold in very large numbersunread，untouched.(These owner sown only wood pulp and ink，not books.)
Another kind of book owners have a great many booksa few of them read through，most of them dipped into，that is，most ofthe books are only read or studied for a short time or without much attention;but all of them as clean and shiny as the day they were bought.(These persons would probably like to make books their own，but are restrained by a false respect for their physical appearance.)
