This is the big moment.

这可是关键时刻。

How true!

千真万确。

Let sleeping dogs lie.

别招惹麻烦。

The important thing is that you tried.

重要的是你已经努力过了。

I know how you feel, but there's no need to go on and on about it.

我知道你的感受，可是也没必要这样没完没了。

Are you kidding?

你在开玩笑吗？