WebClient client = new WebClient();
                client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");                
                Stream data = client.OpenRead("http://www.baidu.com");
                StreamReader reader = new StreamReader(data, Encoding.Default);
                string s = reader.ReadToEnd();
                tb.Text = s;
                reader.Close();
                reader.Dispose();

            XmlDocument doc1 = new XmlDocument();
            doc1.Load("http://manage.adcall.com.cn/public/e0838.jsp?sell_id=00000&adcall_no=9000000000&query_type=4&type=0");