Usually there is only one or two a year bright enough to be seen with the naked eye.

通常，一年只有一到两颗彗星明亮得肉眼可见。

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Don't read or write in poor or bright light because it can cause eye tiredness.

不要在弱光或强光下阅读或写作，因为这会造成眼睛疲劳。

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This is because their colors are not bright enough to be noticed by the human eye.

这是因为它们的颜色不够明亮，无法被人眼注意到。

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The VGA-resolution 3.2-inch display was incredibly sharp and bright, and the vari-angle functionality lets you snap overhead and below-eye-level shots with ease.

ENGADGET: Hands-on with Nikon's Coolpix P520 and L820 superzooms at CP+ (video)

Driven by Lumus' patented Light-guide Optical Element, a micro-display pod, and the Optical Engine which projects light into the lens -- where it is reflected back to the user's eye via reflectors embedded in the lens -- the Lumus' DK-32 delivers a bright 720p 3D-capable display that only weighs 27 grams.

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And the infinite emptiness of the brilliant sky above means that on the rare occasions when an object, such as a plane or a hot-air balloon, does pass through, the bright contrast lends it such a fierce intensity that it confuses the eye.

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