釉质龋中透明层是由于
A．树胶分子进入晶体间隙B．脱矿后的孔隙内不能进入空气C．晶体间出现微小的孔隙D．含氟量高E．再矿化
参考答案：A
I have never seen others _____ so brilliantly. [ ]
A. performing
B. perform
C. to be performed
D. being performed
简述支架产生倾斜的原因？
