A.開(kāi)口于平對(duì)下頜第2磨牙牙冠的頰黏膜上 B.開(kāi)口于平對(duì)上頜第2前磨牙牙冠的頰黏膜上 C.開(kāi)口于平對(duì)上頜第2磨牙牙冠的頰黏膜上 D.開(kāi)口于平對(duì)下頜第2前磨牙牙冠的頰黏膜上 E.由腺體深部的前緣發(fā)出
