----what do you think of the Chinese language today?

----Quite popular. It______ in communicating with other countries. More and more foreign friends are learning Chinese.

A．plays an important role

B．is playing an important role

C．has played an important role

D．is being played an important role

龋病可以被称之为牙硬组织的何种感染性疾病（）

A.病毒

B.细菌

C.真菌

D.支原体

E.衣原体