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。

youdao

Moonbows appear on the opposite side of the moon and usually look white to the human eye.

月虹出现在月亮的另一侧，它们在人眼中通常看起来是白色的。

youdao

Plants are also able to distinguish between specific wavelengths of light that the human eye cannot even see!

植物还能分辨出人类肉眼看不到的特定波长的光！

youdao

Degas and the Impressionists were interested in painting the effects of light, and how the human eye sees subjects.

VOA: special.2009.07.12

I then replaced the wooden boards so well that no human eye -- not even his -- could have seen anything wrong.

VOA: special.2009.05.16

When they used the telescope to create images of the planet, they found an area that appeared dark in light the human eye could see.

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On one screen, quotes blink on and off at speeds barely visible to the human eye.

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The difference, however, is that these mechanics were large enough to be seen with the human eye.

FORBES: Watching Quantum Physics With The Naked Eye

It would respond much in the same was a human eye, moving if something caught its attention, he said.

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