The salient district complementary distribution indicates that the force of the sound change from velar plosive initial before a high front vowel in the northern dialects to a alveolar affricate comes from outside influence rather than internal change .

这种明显的地域互补分布表明了北方汉语方言前高元音前面的舌根声母转变为 舌面 音的力量来自于外部的人文影响，而非内部语言音变。

What is heart mitral valve velar prolapse ?

什么是心脏二尖瓣 膜脱垂？

Since mediaeval times velar and guttural and its opening closing mouth have had many transformations .

中古以来 牙 喉音及其开合口发生了许多变化。