随着课程的深入，作业难度逐渐增加。

The difficulty of the homework increases ___progressively as the course advances.

我们逐步提高难度，让学生更容易掌握知识。

We increase the difficulty ___progressively to help students learn better.

随着练习的深入，他的钢琴技巧变得越来越好。

His piano skills improved ___progressively with more practice.