网页源码
<tr>
       <td align="right" width=250>用户名</td>
       <td align="left" ><input type="text" name="Username" style="width:180px;align:left"></td>
    </tr>
    <tr>
       <td align="right" width=250>密&nbsp;&nbsp;码</td>
       <td align="left"><input type="password" name="Password" style="width:180px;align:left"></td>
    </tr>
    <tr><td align="center" colspan="2" height=20></td></tr>
    <tr>
       <td align="center"></td>
       <td align="left"><input type="submit" value="登  录">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<input type="reset" value="取  消"></td>
    </tr>
使用下列代码不能实现
private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
        {
            HtmlElementCollection hec = webBrowser1.Document.All;
            foreach (HtmlElement hes in hec)
            {
                string str = hes.GetAttribute("type");

                switch(str)
                {
                    case "text": hes.SetAttribute("value", "administrator");break;
                    case "password": hes.SetAttribute("value", "01234567");break;
                    case "submit": hes.InvokeMember("click"); break;
                }
            }
        }

请教该如何修改，谢谢！！