This is a voiceless sound. Put your top teeth slightly over your bottom lip and blow out air quickly. Your tongue should be flat in your mouth.

这是一个轻声。把你的上齿轻轻放在你的下唇并快速发出气流。你的舌头在你的嘴里的时候应该是扁平的。

youdao

For , put your top teeth onto your bottom lip, and make a sound exactly like except voiceless.

发，要用上齿咬住下唇，发出类似的音，同样也不振动声带。

youdao

For , put your top teeth onto your bottom lip, and make a sound exactly like except voiceless.

发，要用上齿咬住下唇，发出类似的音，同样也不振动声带。

youdao