Redouble your efforts and not slacken off.

要再接再励， 不能松劲。

We've been really busy, but things are starting to slacken off now.

近来我们的确很忙，不过现在情况开始有所缓解了。

Nothing could make us slacken off.

什么也不能让我们松劲。

Trade have slacken off.

不要放松紧握着的手。

You shouldn't slacken off in your study.

你不应该松懈你的研究。