— Why do you do volunteer work in the North-West?

— I___ to improve the lives of the children there through my efforts．

A．was trying

B．have tried

C．am trying

D．tried

睫状神经节的节后纤维是（）

A.睫状长神经

B.动眼神经

C.睫状短神经

D.筛后神经

E.滑车下神经