在同学学习排列组合的问题时,常常碰到球放入盒子有关的问题,这类问题的变化较多,学生掌握起来比较困难,且其它一些问题可以转化为球·盒子问题,也即具有模型置换的功能,本文拟就此谈些解决方法. When students learn to arrange and arrange problems, they often encounter problems related to the ball being put into the box. These types of problems have many changes, students are more difficult to master, and other problems can be transformed into ball box problems, that is, have models. Replacement function, this article intends to talk about some solutions.