只实现了一些简单的运算；加减乘除；清零；归零；菜单栏；小数点；错误提示窗口；等等；只要会这些，其他的一些功能自己就一定也会添加了了；-Only implements a few simple operations　subtraction multiplication and division　Clear　zero　menu bar　decimal point　error window　and so on　so long as these, some other features himself would surely be added in