Regex Failure

http://www.codewars.com/kata/55c423ecf847fbcba100002b/train/csharp

Oh no, Timmy's received some hate mail recently but he knows better. Help timmy fix his regex filter so he can be awesome again!

using System;
using NUnit.Framework;
System.Text.RegularExpressions

[TestFixture]
public class Tests
{
  [Test]
  public static void FixedTest()
  {
    Assert.AreEqual("You're awesome! timmy!", Kata.filterWords("You're Bad! timmy!"));
    Assert.AreEqual("You're awesome! timmy!", Kata.filterWords("You're MEAN! timmy!"));
    Assert.AreEqual("You're awesome!! timmy!", Kata.filterWords("You're UGLY!! timmy!"));
    Assert.AreEqual("You're awesome! timmy!", Kata.filterWords("You're horrible! timmy!"));
    Assert.AreEqual("You're awesome!! timmy!", Kata.filterWords("You're HiDeOuS!! timmy!"));
    Assert.AreEqual("You're awesomeish!! timmy!", Kata.filterWords("You're Meanish!! timmy!"));
  }
}

主要是i的用法，

i

Use case-insensitive matching.

(?i)a(?-i)aw+

"aardvark", "aaaAuto" in "aardvark AAAuto aaaAuto Adam breakfast"

using System;
using System.Text.RegularExpressions;

public class Kata
{
  public static string filterWords(string phrase)
  {
      string pattern = @"(?i)bad|mean|ugly|horrible|hideous";
      string replacement = "awesome";
      Regex rgx = new Regex(pattern);
      return rgx.Replace(phrase, replacement);
  }
}