HttpWebRequest AsyncCallback参数问题

当我尝试在第一个方法中单击to按钮时，它在for循环中创建异步http请求。但是，我不能将参数传递给异步回调函数。我想用POST方法在for循环中发送id

    void Button3Click(object sender, EventArgs e)
    {            
        for(int i = Convert.ToInt32(startno3.Text); i<Convert.ToInt32(endno3.Text); i++) {                
            ASCIIEncoding encoding=new ASCIIEncoding();
            string postData="id=1";                
            qstr3 = encoding.GetBytes(postData);                
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost/ornek/1.php");
            if(key1.Text!="") {
                request.Headers.Add("Cookie", "PHPSESSID=" + key1.Text);                    
            }
            request.Method = "POST";
            request.ContentType="application/x-www-form-urlencoded";
            request.ContentLength = data.Length;
            IAsyncResult asyncResult = request.BeginGetResponse( new AsyncCallback(EndScanFeeds), request);    
        }
    }
    public void EndScanFeeds(IAsyncResult result) {
        HttpWebRequest request = null;
        HttpWebResponse response = null;
        Stream stream = null;
        StreamReader streamReader = null;
        try {
            request = (HttpWebRequest)result.AsyncState;
            response = (HttpWebResponse)request.EndGetResponse(result);
            stream = response.GetResponseStream();
            streamReader = new StreamReader(stream);
            string feedData = streamReader.ReadToEnd();
            response.Close();
            stream.Close();
            streamReader.Close();
            MessageBox.Show(feedData);
        }
        catch(Exception ex) {
            throw(ex);
        }
        finally {
            if(response != null)
                response.Close();
            if(stream != null)
                stream.Close();
            if(streamReader != null)
                streamReader.Close();
        }
    }   c