动态改变ComboBox的内容，可以动态添加或者删除ComboBox下拉列表的值-dynamic change ComboBox content, can dynamically add or delete ComboBox drop-down list values

基于vc++6.0MFC进行列表控件的编程和按钮添加、删除、修改的编程-Based on vc++ 6.0MFC list control of the programming and button to add, delete, modify the programming