C# webBrowser 填写表单

        private void Reg()
        {
            HtmlElement a = webBrowser1.Document.GetElementById("Email");
            a.InnerText = "bauyew@hotmail.com";
            a = webBrowser1.Document.GetElementById("Passwd");
            a.InnerText = "thanks888";
            a = webBrowser1.Document.GetElementById("PasswdAgain");
            a.InnerText = "thanks888";
            a = webBrowser1.Document.GetElementById("creditcard.CreditCardNumberTextField");
            a.InnerText = "4530930055503055";
            a = webBrowser1.Document.GetElementById("creditcard.ccExpMonth");
            a.SetAttribute ("SelectedIndex", "10");
            a = webBrowser1.Document.GetElementById("creditcard.ccExpYear");
            a.SetAttribute("SelectedIndex", "03");
            a = webBrowser1.Document.GetElementById("creditcard.CreditCardCvvTextField");
            a.InnerText = "066";
            a = webBrowser1.Document.GetElementById("creditcard_name");
        //    a.InvokeMember("click");
          // a.InnerText = ("Wallace Keynes");
           a.SetAttribute("value", "webcheck");

           a = webBrowser1.Document.GetElementById("creditcard_street1");
            a.InnerText = ("9276 Balsam Cres");
            a = webBrowser1.Document.GetElementById("creditcard_town");
            a.InnerText = "Mount";
            a = webBrowser1.Document.GetElementById("creditcard_state_menu");
            a.SetAttribute("SelectedIndex", "1");
            a = webBrowser1.Document.GetElementById("creditcard_zip");
            a.InnerText = "36010";
            a = webBrowser1.Document.GetElementById("creditcard.phone");
            a.InnerText = "334 808 6870";
;
HtmlElement btnSubmit = webBrowser1.Document.GetElementById("submitbutton");
         //     btnSubmit.InvokeMember("click");
          
        }