— 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
网友回答
A. was trying
B. have tried
(答案→)C. am trying
D. tried
解析：句意：--你为什么在西北做志愿者的工作？--我在努力通过自己的努力改善那里孩子的生活。从第一句话：Why do you do volunteer work in the North-West?可知是现在正在做，用现在进行时，选C。