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;

        }