asp.net 在线翻译问题

前台

<%----%>

	请选择 英语到中文(繁体) 英语到中文(简体) 中文到英语 中文(繁体到简体) 中文(简体到繁体)

后台

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net;
using System.IO;
using System.Text;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void Submit1_ServerClick(object sender, EventArgs e)
{
string langpair = Select1.Value.Trim();
Response.Write(langpair);
Response.Write("
");
string word = TEXTAREA1.Value.Trim();
Response.Write(word );
Response.Write("
");
string url = @"http://translate.google.cn/translate_t?langpair="+langpair+ "&text="+word+"";
Response.Write(url);
Response.Write("
");
WebRequest req = WebRequest.Create(url);
WebResponse res = req.GetResponse();
Stream s = res.GetResponseStream();
StreamReader sr = new StreamReader(s, Encoding.Default);
char[] cs = new char[1024];
string str = sr.ReadToEnd();
int i = str.IndexOf("", i + 29);
string result = str.Substring(i + 29, j - i - 29);
TEXTAREA1.Value=result;
}
}

测试可以实现英文翻译中文 中文翻译英文出现问题（暂时未解决）
C# 要转化为服务器控件， 由服务器控件响应