插入式电阻箱的使用原则是：用的不插，插的不用。这一原则与人们的思维习惯相反，在实际教学中，学生经常会出现判断错误。为了解决这一问题，我制作了发光显示的插入式电阻箱，使学生能直观地了解插入式电阻箱的使用原则。具体制法如下：选用长为40cm、宽为ZOcm的三合板一块? Plug-in resistance box is the use of the principle: the use of the plug, plug the useless. This principle is contrary to people’s thinking habits. In practical teaching, students often make mistakes in their judgments. In order to solve this problem, I made a light-emitting display plug-in resistance box, so that students can intuitively understand the principle of the use of plug-in resistance box. The specific method of manufacture is as follows: Select a piece of plywood with a length of 40cm and a width of ZOcm?