private void CreateWAVFile(string text)
        {
            SaveFileDialog sfd = new SaveFileDialog();
            sfd.Filter = "所有文件 (*.*)|*.*|WAV 格式文件 (*.wav)|*.wav";
            sfd.Title = "保存到 wave 文件";
            sfd.FilterIndex = 2;
            sfd.RestoreDirectory = true;
            if (sfd.ShowDialog() == DialogResult.OK)
            {
                SpeechStreamFileMode SpFileMode = SpeechStreamFileMode.SSFMCreateForWrite;
                SpFileStream SpFileStream = new SpFileStream();
                SpFileStream.Open(sfd.FileName, SpFileMode, false);
                speech.AudioOutputStream = SpFileStream;
                speech.Rate = -1;
                speech.Volume = volume;
                speech.Speak(text, SpeechVoiceSpeakFlags.SVSFlagsAsync);
                speech.WaitUntilDone(Timeout.Infinite);
                SpFileStream.Close();
            }
        }