这些都说起来容易，但是很难做到。

All this is easy to say, but hard to do.

youdao

对，我知道，但是很难做到。

B: Yeah, I know, but it's too hard to do.

youdao

非常经典，但是很难做到，需要很高的心里素质。

It is very classical! But it is very hard to achieve. You must have a very strong heart.

youdao

There may be circumstances under which it's the case but it's often difficult to control.

可能在某些环境下可以做到,但是通常情况下很难控制。

麻省理工公开课 - 热力学与动力学课程节选