Apples are usually sold by ________ weight and eggs are sometimes sold by ________ dozen.

A．the; the

B．/;a

C．/; the

D．the; a

龋病的一级预防不包括（）

A.窝沟封闭

B.应用氟化物

C.早期充填

D.合理饮食

E.口腔健康教育