Unless you work as hard as you can, you won’t your classmates.
A. fall behind
B. keep on with
C. keep up with
D. catch up
网友回答
A. fall behind
B. keep on with
(答案→)C. keep up with
D. catch up
解析：本题考查动词短语辨义。句意: 如果你不尽可能的努力学习，你就跟不上你的同学。fall behind 落后；keep on不和with搭配；keep up with跟上……，不落后于；catch up跟上……；后接with后才可接宾语。