Our school has school rules, and our class also has class rules. We can’t have breakfast in the classroom. Our teacher says we will make our books become dirty if we eat in classroom. Then it becomes the class rules in my class. If anyone breaks this rule, he will be punished. So no one in my class dare to have breakfast in the classroom.

http://www.englishc.com/html/yingyuyishu/dianying/20080216/1708.html
这里有一篇哈~