private void button1_Click(object sender, EventArgs e)

{

  ((Button)sender).Text = "Clicked!";

  Button newButton = new Button();

  newButton.Text = "New Button!";

  newButton.Click += new EventHandler(newButton_Click);   

 //请问这里的+=不是先加后赋值运算符么，请问这一句怎么解释;

  Controls.Add(newButton);

}

private void newButton_Click(object sender, System.EventArgs e)

{

  ((Button)sender).Text = "Clicked!!";

//上面这一句里面的sender又是干嘛的,百度了一下，说是有多个按钮的时候用的

}