In the production of these sounds, the upper and the lower lips are brought together to create obstruction. The English bilabials are [p] [b] [m] [w].
本题考查辅音中双唇音的发音方式。
双唇音，指的是在发这类语音的时候，上唇和下唇合在一起来形成阻碍。英语里的双唇音有[p] [b] [m] [w]。
