A rainbow rose against the dark sky.

昏黑的天空中出现一道彩虹。

《新英汉大辞典》

“I can’t…” the Rainbow Fish started to say, but the octopus had already disappeared into a dark cloud of ink.

“可是......” 彩虹鱼刚想再说些什么，章鱼已经消失在漆黑的墨汁里了。

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This juxtaposition has been called Dark Side of the Rainbow.

这个作品的名字叫《彩虹之暗面》。

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The spectrum of light that emerges from such a container will show a series of dark lines interrupting what would be a continuous rainbow.

ECONOMIST: Fundamental physics

The four-hour event ended with everyone holding hands and singing a song with the lyrics "You have to go through a thunderstorm to see a rainbow"--a reference to the dot-com bust and the dark days of the SARS virus scare as Taobao launched in mid-2003.

FORBES: OutFront