怎么 过滤 这种标签

如何 过滤 这种标签
<FONT style="FONT-SIZE: 10pt" face=微软雅黑 color=#000000>
还有&nbsp;希望换成空格
其他标签 都换成 需要的 


[解决办法]
如果需要替换特殊标记，自己匹配正则，然后替换

C# code

public static string EncodeHtml(this string str,string Htmlstring)        {            if (!string.IsNullOrEmpty(str))            {                //删除脚本                 Htmlstring = Regex.Replace(Htmlstring, @"<script[^>]*?>.*?</script>", "", RegexOptions.IgnoreCase);                //删除HTML                 Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);               // Htmlstring = Regex.Replace(Htmlstring, @"([/r/n])[/s]+", "", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"-->", "", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"<!--.*", "", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(quot|#34);", "/", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(amp|#38);", "&", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(lt|#60);", "<", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(gt|#62);", ">", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(nbsp|#160);", "   ", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(iexcl|#161);", "/xa1", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(cent|#162);", "/xa2", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(pound|#163);", "/xa3", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&(copy|#169);", "/xa9", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"&#(/d+);", "", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"(^\\s*)|(\\s*$)", "", RegexOptions.IgnoreCase);                Htmlstring = Regex.Replace(Htmlstring, @"^( )+|^[\\s　]+|( )+$|[\\s　]+$", "", RegexOptions.IgnoreCase);                Htmlstring.Replace("<", "");                Htmlstring.Replace(">", "");                Htmlstring.Replace("\r\n", "");                Htmlstring.Replace("\t", "");                Htmlstring = HttpContext.Current.Server.HtmlEncode(Htmlstring).Trim();            }            else            {                Htmlstring = null;            }            return Htmlstring;        }