WebRequest定义体参数 - C＃中的方法POST

Question

我有代码：   var request =

(HttpWebRequest)WebRequest.Create("http://www.dba.dk/ajax/vip/telephonenumber/gettelephonenumber/?externalid=1033601271");

            string stringData = "externalid=1033601271";
            var data = Encoding.ASCII.GetBytes(stringData);

            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
            request.ContentLength = data.Length;
            var newStream = request.GetRequestStream();
            newStream.Write(data, 0, data.Length);
            newStream.Close();
            WebResponse response = request.GetResponse();
            MessageBox.Show(((HttpWebResponse)response).StatusDescription);
            response.Close();

有了这个，我收到了来自服务器的400 Bad Request。我想，我需要定义请求正文： - 我检查的Firefox网络分析仪应该是这样的：外部ID = 1033601271＆放大器; __ RequestVerificationToken = Xd5coguwXJArf6-5mQNl8eXOoBpUEltnpq2SvVfLSfo6Fe5MAw4VoaWT89NPEFJPONppjePDF5mWVO1CzMbGqqWA1KS2M8ZXmpJ0DNExcSCrxCIPPF_pBjP7lkRbt-rs9HrpHQ2

我如何在我的代码中定义它？另外我如何读取服务器到字符串变量的响应？