both his eyes focused on his book, he didn’t notice me enter the room.

A．Through

B．Because of

C．For

D．With

性病是指通过性行为或类似性行为传播的一组传染性疾病。性传播疾病是可以预防的。

利用各种媒介向大众宣传性病的传播途径和有效预防措施是（）

A.二级预防

B.三级预防

C.先期预防

D.一级预防

E.原级预防