在窗体上创建4个命令按钮，分别为Command1、Command2、Command3和Command4。分别编写4个命令按钮的Click事件代码和Form1_Load（）事件代码。-On the form to create a command button, Command1, Command2, Command3 Command4. The preparation of 4 command button' s Click event code and Form1_Load () event code.