work hard at

• v. 努力工作或学习

work hard at的用法和样例：

例句

1. He worked hard at his biology.
   他努力学习生物学。
2. If you work hard at other times, you won't have to sit up all night before the exam.
   你平时如果努力学习，在考试前就不必这样整夜开夜车了。