It's going to rain, because the dark clouds are gathering and hanging lower and lower.

就要下雨了，因为乌云密布，而且越压越低了。

youdao

Rather, they are dark because of interstellar dust that hides the stars behind it.

相反，它们之所以是黑暗的，是因为星际尘埃将恒星隐藏在它的后面。

youdao

The tugboat is small and dark and it's making a lot of smoke, but it's very strong, because it's pulling the much bigger ship.

拖船又小又黑，还冒着很多烟，但它非常有力，因为它在拖着比它更大的船。

youdao

This is because lighter colors take in less of the strong heat of the sun than dark colors do.

VOA: special.2009.08.19

That's because it's here where the rigid polarities between light and dark and good and evil, all of these absolute oppositions, begin to collapse.

这是因为这里就是光与暗,善与恶之间严格的两极分化，及所有绝对的对比开始崩塌的地方。

耶鲁公开课 - 弥尔顿课程节选

I'm usually out early in the morning when it's still dark now because of the changing in the season.

我通常早上很早就出门，因为季节变换，那时天还是黑的。

中央公园的时光 - SpeakingMax英语口语达人

But she can't see Clayton Buller's eyes because of the dark glasses he wears, and DI Pendle doesn't seem to be alarmed.

CNN: Books - Excerpt: 'Flint'

Keep the gruesome stuff because it makes the game dark and scary and wonderful.

FORBES: [Spoilers follow.]

One thing that may not be happening is agreement on the scheduling of a backbench debate on an "in-out" referendum on the EU. But this will not be because of any dark machinations by the whips.

BBC: Viewing guide: The coming week's highlights in Parliament