mouth shape的用法和样例：
例句
- Tamber is influenced by many factors such as mouth shape, tongue shape, breath, pose and harmonica itself.
口琴的音色受很多因素的影响，比如口形，舌头的位置，呼吸方式，持琴姿势，琴本身的音色特性，甚至录音也会对其产生影响。 - One day in the class I could not pronounce a diphthong - not opening my mouth wide enough - since I was from the Northeast, no matter how many times Teacher Zhang corrected me.
有一次，张老师纠正我的发音，说我这个东北人，双元音口形总是张不开，一再娇正也发不好。
