牙髓病最常见的是（）。
A.牙髓充血
B.牙髓炎
C.牙髓坏死
D.牙髓钙变
E.牙内吸收
参考答案：B
Before graduation, we had got a lot of practical _____ by doing a part-time job in the factory and it was really ______ for all of us.
A．experiences; great experience
B．experience; great experience
C．experiences; a great experience
D．experience; a great experience
归因理论是从______来阐述行为动机的。
