如何显示哪些子正则表达式不匹配?

我正在使用正则表达式验证用户输入。以下代码收集可通过themich.groups[标识符]访问的匹配项。如何获取每个组中不匹配的子字符串列表?

#region Using directives

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;


namespace RegExGroup
{

   class Test
   {
      public static void Main( )
      {
         string string1 = "04:03:27 127.0.0.0 comcom.com";

         // group time = one or more digits or colons followed by space
         Regex theReg = new Regex( @"(?<time>(\d|\:)+)\s" +
         // ip address = one or more digits or dots followed by  space
         @"(?<ip>(\d|\.)+)\s" +
         // site = one or more characters
         @"(?<site>\S+)" );

         // get the collection of matches
         MatchCollection theMatches = theReg.Matches( string1 );

         // iterate through the collection
         foreach ( Match theMatch in theMatches )
         {
           if ( theMatch.Length != 0 )
           {
            Console.WriteLine( "\ntheMatch: {0}",
               theMatch.ToString( ) );
            Console.WriteLine( "time: {0}",
               theMatch.Groups["time"] );
            Console.WriteLine( "ip: {0}",
               theMatch.Groups["ip"] );
            Console.WriteLine( "site: {0}",
               theMatch.Groups["site"] );
           }
         }
      }
   }
}

那么,如果用户输入0xx:03:27 127.0.0.0?com
我想输出

 time:  0xx:03:27
 site:  ?.com

另外,有人对在C中使用regexs有很好的参考。
谢谢,谢谢你的帮助。