To master a foreign language like English requires hard work, so you can't study too hard.

掌握一门像英语这样的外语需要勤奋学习，因此你再怎么努力也不为过。

youdao

For me this was a hard skill to master.

对我而言，这是一个很难掌握的技巧。

youdao

In practice, they are hard to comprehend and master, especially for programmers who are making a transition to object-oriented application development.

在实际中，它们很难理解和掌握，特别是对于那些正在向面向对象应用程序开发过渡的程序设计人员。

youdao

And, if he still has the relentless desire for success he had as a player, the 50-year-old Glaswegian will prove a hard task-master.

BBC: SPORT | Football | My Club | Motherwell | McGhee out to make his mark

As an individual, Sir David was a hard task-master.

BBC: By BBC News online's Nick Assinder

It's always hard to say how much this kind of personal branding contributes to the success of a business, especially one like fish-farming that's easy to enter but hard to master.

FORBES: Magazine Article