I feel it hard to keep up with my classmates in study and sometimes I lose heart. But when

问题补充：

I feel it hard to keep up with my classmates in study and sometimes I lose heart. But whenever I want to , my teacher always encourages me to work harder.

A. go on

B. run away

C. give up

D. look out

答案：

A. go on

B. run away

(答案→)C. give up

D. look out

解析：本题的含义应该为当我想放弃的时候，老师总是鼓励我更加努力的学校，give up表示放弃的意思，符合题意，故本题选C。