Base on the shape of the mouth (rounded, unrounded),the vertical position of the tongue (high, half-low, and low),and the horizontal position of the tongue (front, central, and back).

• 根据唇形（圆唇、不圆唇），舌位的垂直位置（高、半高、半低、低），舌位的水平位置（前、中、后）