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：本题的含义是如果你不尽可能地努力学习，你将不能赶得上你的同班同学，keep up with表示赶得上的意思，符合本题的含义，故本题选C。