Later it was noticed that the explanatory power of the theory, as well as its elegance, were enhanced if a third element were added, our *h1, which has the same lengthening and syllabifying properties as the other two but has no effect on the color of adjacent vowels.
他 跑了 , 他 跑了 , 往 房子 方向 跑LASER-wikipedia2 LASER-wikipedia2