If you work hard ____,you won't have to sit up all night before the exam.

问题描述:

If you work hard ____,you won't have to sit up all night before the exam.
A.by yourself B.at other times C.willingly D.with some help

B
如果你在别的时间里用功读书,就不至于在考前熬夜了.
这里是强调时间上的对比.