How to make the sounds
For the sound, first make the sound, and then use your voice. is voiceless, is
voiced. To make the sound, try making the sound with a /d/ in front of it. In ,
the tip of the tongue touches the tooth ridge; in , it does not.
要发的音，首先发的音（方法见Unit 5）,然后振动声带发声。 是不发声的，是发声的。要发的音，先发的音再在前面发/d/的音。在音中，舌尖要碰到牙床，而是不需要的。
详细的发音方法请参见视频