hard

老师对我们的作业要求比以前更严格了。

The teacher's requirements for our homework are ___harder than before.

这个项目是我做过的最困难的工作。

This project is the ___hardest work I've ever done.

我觉得数学考试很难。

I think the math test was very ___hard.

我妈妈工作很辛苦。

My mum works very ___hard.

为了通过考试，他学习得非常刻苦。

He studied ___hard to pass the exam.