SAPI v5.1的帮助SpeechRecognitionEngine与C＃总是给出相同的错误结果

    private void button1_Click(object sender, EventArgs e)
    {
        //Add choices to grammar.
        Choices mychoices = new Choices();
        mychoices.Add(\"one\");
        mychoices.Add(\"two\");
        mychoices.Add(\"three\");
        mychoices.Add(\"four\");
        mychoices.Add(\"five\");
        mychoices.Add(\"six\");
        mychoices.Add(\"seven\");
        mychoices.Add(\"eight\");
        mychoices.Add(\"nine\");
        mychoices.Add(\"zero\");
        mychoices.Add(\"1\");
        mychoices.Add(\"2\");
        mychoices.Add(\"3\");
        mychoices.Add(\"4\");
        mychoices.Add(\"5\");
        mychoices.Add(\"6\");
        mychoices.Add(\"7\");
        mychoices.Add(\"8\");
        mychoices.Add(\"9\");
        mychoices.Add(\"0\");

        Grammar myGrammar = new Grammar(new GrammarBuilder(mychoices));

        //Create the engine.
        SpeechRecognitionEngine reco = new SpeechRecognitionEngine();

        //Read audio stream from wav file.
        reco.SetInputToWaveFile(\"3.wav\");
        reco.LoadGrammar(myGrammar);

        //Get the recognized value.
        reco.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(reco_SpeechRecognized);

        reco.RecognizeAsync(RecognizeMode.Multiple);
    }

    void reco_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
    {
        MessageBox.Show(e.Result.Text);
    }