龋洞充填后，嵌塞的原因有（）
A.邻接点恢复不良
B.充填体有悬突
C.充填时用了成形片
D.充填材料次
E.外展隙小
参考答案：A, B, E
火眼金睛，选词填空。
1. This is _____________ (a, an) ice-cream.
2. These _____________ (photos, photoes) are very nice.
3. I like reading _____________ (book, books).
4. There are five _____________ (knifes, knives).
5. She can _____________ (makes, make) kites.
若DIF是正值，说明短期的比长期的平滑移动平均线低。 ( )
