要想练好一种乐器，你必须持之以恒。

If you want to play an instrument well, you've got to stick at it.

《牛津词典》

你必须持之以恒，坚持运用你的知识。

You have to persevere and persist in applying your knowledge.

youdao

首先，必须感兴趣，其次必须持之以恒。

First of all, you must be interested in it. And then, you should make constant efforts.

youdao

It's definitely a practice you have to do constantly and consistently.

这是必须要进行的练习,要坚持不懈，持之以恒。

普林斯顿公开课 - 人性课程节选

It's something you can keep working on, that I need to keep working on, even Professor Raboteau needs to keep working on.

大家必须做到持之以恒，这也是我所追求的，甚至Raboteau教授也是一样。

普林斯顿公开课 - 人性课程节选