.net c# 如何获指定地址的网页内容标签

//捉取页面
    protected void Button1_Click(object sender, EventArgs e)
    {
        WebRequest webRequest = WebRequest.Create(this.txtSearch.Text.Trim());

        WebResponse webResponse = webRequest.GetResponse();

        Stream stream = webResponse.GetResponseStream();

        //StreamReader sr = new StreamReader(stream);

        StreamReader sr = new StreamReader(stream, Encoding.Default);
        StringBuilder sb = new StringBuilder();

        string str=string.Empty;

        while ((str = sr.ReadLine()) != null)
        {
            sb.Append(str).Append("<br/>");
        }

        this.div.Value = sb.ToString();
        this.div2.InnerHtml = sb.ToString();

    }