Asynchronously recognizing speech based on a restricted set of phrases

SpeechRecognitionEngine recognitionEngine = new SpeechRecognitionEngine();
GrammarBuilder builder = new GrammarBuilder();
builder.Append(new Choices("I am", "You are", "He is", "She is", "We are", "They are"));
builder.Append(new Choices("friendly", "unfriendly"));
recognitionEngine.LoadGrammar(new Grammar(builder));
recognitionEngine.SpeechRecognized += delegate(object sender, SpeechRecognizedEventArgs e)
{
    Console.WriteLine("You said: {0}", e.Result.Text);
};
recognitionEngine.SetInputToDefaultAudioDevice();
recognitionEngine.RecognizeAsync(RecognizeMode.Multiple);