They do chores at home and hopefully manage to find some time to study before it gets dark.

他们在家做家务，希望能在天黑前找到时间学习。

youdao

Before it gets dark, I'll come back.

天黑以前我会回来。

youdao

I'll water the flowers before it gets dark.

我要趁着天还没黑把花浇好水。

youdao

That leaves just four. I want to see the last one fall before it gets dark.Then I'll go,too."

VOA: special.2009.08.01

Maybe you should leave before it gets too dark, so that you don't have to walk too far.

也许你该在天黑之前就动身回去了，这样你就不用走那么远了。

How long实战 - SpeakingMax英语口语达人