牙震荡主要损伤（）。

A.牙龈

B.牙本质和牙槽骨

C.牙周膜

D.牙髓

E.牙周膜和牙髓

So well         in 2009 that the world has agreed that it was the year of China.

A．did China perform

B．China has performed

C．was China performed

D．China is performing