That's a weight off my mind

We use this expression when we were worried about something but now the situation has changed and we are not worried any more

我们用这个短语来表达当我们我们一度非常担心一件事但是现在情况出现转机，我们不再去担心它的心理，就像我们常说的“心里一块石头总算落地了;这样我就放心了”

A：Don't worry, you don't need to work late tomorrow night. I'll do it.

不用担心了，你今天晚上不必加班了。我会做完它的。

B: Oh thanks. That's a weight off my mind.

哦，那真是太感谢了。我心里的一块石头总算落地了。