Windows Phone中的WebBroswer查询

我有以下代码，但是当我构建它时，我在WebBrowserDocumentCompletedEventArgs上收到错误，告诉我无法找到类型或命名空间。

我一直在网上搜索并尝试添加DLL超过一个小时。 有人可以帮忙吗？

private void b_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { WebBrowser b = sender as WebBrowser; string response = b.DocumentText; // looks in the page source to find the authenticity token. // could also use regular expressions here. int index = response.IndexOf("authenticity_token"); int startIndex = index + 41; string authenticityToken = response.Substring(startIndex, 40); // unregisters the first event handler // adds a second event handler b.DocumentCompleted -= new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted); b.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted2); // format our data that we are going to post to the server // this will include our post parameters. They do not need to be in a specific // order, as long as they are concatenated together using an ampersand ( & ) string postData = string.Format("authenticity_token={2}&session[username_or_email]={0}&session[password]={1}&commit={3}", username, password, authenticityToken, commit); ASCIIEncoding enc = new ASCIIEncoding(); // we are encoding the postData to a byte array b.Navigate("https://twitter.com/sessions", "", enc.GetBytes(postData), "Content-Type: application/x-www-form-urlencoded\r\n"); }