25.1 Definition and Classification(定义与分类)
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.
在进行定义或分类写作时需注意：1)在进行诠释(定义)时，一定要具体、确切;2)分类时要周密，标准必须对应划一，不能交错重叠。
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.)
