—Did you know any French before you arrived in Washington? —Never ___ it, actually．

A．had I learned

B．have I learned

C．I learned

D．was I learning

对健康影响作用越来越大的因素是（）

A.卫生服务

B.自然环境

C.生物学

D.行为与生活方式

E.社会环境