函数是高中数学最重要的概念之一 ,函数知识是贯穿在中学数学中的一条主线 ,因而对函数的理解应高度重视 ;函数是其定义域到值域的一种映射 ,是一种特殊的对应关系 ,但由于其抽象性 ,许多同学常会因理解上的不足 ,解题时出现这样或那样的错误 .下面笔者试图用几个简单的事例 , Functions are one of the most important concepts in high school mathematics. Function knowledge is a thread that runs through middle school mathematics. Therefore, the understanding of functions should be highly valued; functions are a mapping from their domain to the value domain, and they are special. Correspondence, but due to its abstract nature, many classmates often suffer from comprehension deficiencies, and when they solve problems, they have one or more mistakes. The following author tried to use a few simple examples.