Many of the electronic devices we use every day, like our phones and computer screens, give off blue light.

我们每天使用的许多电子设备，比如手机和电脑屏幕，都会发出蓝光。

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The ‘Normal’ setting is for day-to-day classroom activities, while Energy gives a blue tint to the light to invigorate pupils when they need to be more active.

据悉，这种“起床灯”开到正常亮度时，可以保证学生在教室的正常听课质量，当把该灯调到蓝色光源时，该灯可以及时“鼓舞”学生士气，让他们变得更积极，从睡梦中醒来。

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He seated himself there, as on the preceding day, surveying from a distance, and clearly making out, the white bonnet, the black dress, and above all, that blue light.

和前一天一样，他在那里坐了下来，从远处了望，清清楚楚地看见了那顶白帽子，那件黑裙袍，尤其是那一片蓝光。

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But a clear, cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more easily than they do red light.

BBC: rainbow

He had on a light-blue shirt, buttoned to the top and wrinkled by sweat it was a warm day, and there was not much of a breeze on the patio.

NEWYORKER: Alone