private void Form1_Load(object sender, EventArgs e)        {            webBrowser1.Navigate("http://www.baidu.com");            webBrowser1.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowser1_DocumentCompleted);        }        void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)        {            webBrowser1.Document.MouseUp += new HtmlElementEventHandler(Document_MouseUp);        }        void Document_MouseUp(object sender, HtmlElementEventArgs e)        {            IHTMLDocument2 document = (IHTMLDocument2)webBrowser1.Document.DomDocument;            IHTMLTxtRange htmlElem = (IHTMLTxtRange)document.selection.createRange();            string s = htmlElem.htmlText;            richTextBox1.Text = s;        }