Blue flies into the sky, so the sky is blue.

蓝色飞入天宇，所以天空是蓝的。

youdao

What is blue? The sky is blue.

什么是蓝色的？天空是蓝色的。

youdao

We see the sky is blue, but down in the valley it's darker—it's like on a cloudy day.

我们看到天空是蓝色的，但山谷下面却很暗——就像阴天一样。

youdao

The sky is blue, the air is crisp and the leaves are aflame with gold, crimson and orange.

BBC: In Boston, leaf peeping by bike

And the sky is blue, it says, because the sun produces white light which is made up of all the colours of the rainbow.

BBC: rainbow

Folks argue about whether the sun rises in the east and whether it sets in the west, whether the sky is blue. (Laughter.) There's always going to be arguments in Washington.

WHITEHOUSE: President Obama Speaks on Skills for American Workers