A.唇颊侧止于唇颊黏膜与牙槽嵴唇颊黏膜的反折线，让开唇颊系带
B.下颌舌侧止于口底黏膜与牙槽嵴舌侧黏膜的反折线，让开舌系带
C.上颌后缘止于腭小凹两侧翼上颌切迹的连线
D.下颌后缘止于磨牙后垫的1/2～2/3
E.以上均正确