—If people make small changes, like taking buses instead of driving cars, it will make a big difference.

—_____. Then the traffic will be much better.

A．That’s all right

B．You are right

C．I don’t quite agree

D．Oh, come off it

以下哪项不是龋病的特征（）

A.为常见病，多发病之一

B.为牙体硬组织的细菌感染性疾病

C.牙体硬组织在色形质各方面均发生变化

D.基本变化为有机物分解和无机物脱矿

E.能不经治疗自行修复