当单击第一个按钮时，按钮上的文字“这里是一个按钮，按我吧!”就变成“你已按下了按钮”，第二个按钮实现转换功能同上，还包含单选按钮，复选按钮及组框控件等。-When you click the first button, the text on the button, " Here is a button, press me!" Becomes " You have pressed the button," the second button to achiev