Clear text Html tags

/// <summary>  
/// 清除文本中Html的标签  
/// </summary>  
/// <param name="Content"></param>  
/// <returns></returns>  
protected string ClearHtml(string Content)
{
    Content = ReplaceHtml("&#[^>]*;", "", Content);
    Content = ReplaceHtml("</?marquee[^>]*>", "", Content);
    Content = ReplaceHtml("</?object[^>]*>", "", Content);
    Content = ReplaceHtml("</?param[^>]*>", "", Content);
    Content = ReplaceHtml("</?embed[^>]*>", "", Content);
    Content = ReplaceHtml("</?table[^>]*>", "", Content);
    Content = ReplaceHtml(" ", "", Content);
    Content = ReplaceHtml("</?tr[^>]*>", "", Content);
    Content = ReplaceHtml("</?th[^>]*>", "", Content);
    Content = ReplaceHtml("</?p[^>]*>", "", Content);
    Content = ReplaceHtml("</?a[^>]*>", "", Content);
    Content = ReplaceHtml("</?img[^>]*>", "", Content);
    Content = ReplaceHtml("</?tbody[^>]*>", "", Content);
    Content = ReplaceHtml("</?li[^>]*>", "", Content);
    Content = ReplaceHtml("</?span[^>]*>", "", Content);
    Content = ReplaceHtml("</?div[^>]*>", "", Content);
    Content = ReplaceHtml("</?th[^>]*>", "", Content);
    Content = ReplaceHtml("</?td[^>]*>", "", Content);
    Content = ReplaceHtml("</?script[^>]*>", "", Content);
    Content = ReplaceHtml("(javascript|jscript|vbscript|vbs):", "", Content);
    Content = ReplaceHtml("on(mouse|exit|error|click|key)", "", Content);
    Content = ReplaceHtml("<\\?xml[^>]*>", "", Content);
    Content = ReplaceHtml("<\\/?[a-z]+:[^>]*>", "", Content);
    Content = ReplaceHtml("</?font[^>]*>", "", Content);
    Content = ReplaceHtml("</?b[^>]*>", "", Content);
    Content = ReplaceHtml("</?u[^>]*>", "", Content);
    Content = ReplaceHtml("</?i[^>]*>", "", Content);
    Content = ReplaceHtml("</?strong[^>]*>", "", Content);
    string clearHtml = Content;
    return clearHtml;
}
/// <summary>  
/// 清除文本中的Html标签  
/// </summary>  
/// <param name="patrn">要替换的标签正则表达式</param>  
/// <param name="strRep">替换为的内容</param>  
/// <param name="content">要替换的内容</param>  
/// <returns></returns>  
private string ReplaceHtml(string patrn, string strRep, string content)
{
    if (string.IsNullOrEmpty(content))
    {
        content = "";
    }
    Regex rgEx = new Regex(patrn, RegexOptions.IgnoreCase);
    string strTxt = rgEx.Replace(content, strRep);
    return strTxt;
}