Unless you work as hard as you can you won’t your classmates. A. fall behindB. keep on w

问题补充：

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

答案：

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。