C# EeventHandler传递参数

C#开发，需要给EventHandler传递一个参数，写法如下：

string serialNumber = "xxx"; 
btn.Click += delegate (object sender, EventArgs e) { openForm(sender, e, serialNumber); };

private void openForm(object sender, EventArgs e, string serialNumber)
{
    this.serialNumber = serialNumber;
}

参考：Passing Parameters to Events - C#