牙龈失去食物生理性按摩作用，引起牙龈废用性萎缩是因（）

A.牙冠轴面凸度正常

B.牙冠轴面凸度过小

C.牙冠轴面凸度过大

D.牙冠轴面呈凸面

E.牙冠轴面呈凹面

His words reminded me        a woman had told me before.

A．that

B．of which

C．what

D．of what