---- If he_____ , he ______ that food.              

---- Luckily he was sent to the hospital immediately.

A．was warned; would not take

B．had been warned; would not have taken

C．would be warned; had not taken

D．would have been warned; had not taken

泪液粘液层的主要功能是（）。

A、冲洗湿润角膜和结膜

B、形成良好的屈光界面

C、外界空气中的氧气被角膜接受和利用的必要条件

D、维持角膜的亲水性