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?