The light they saw in the sky might have been light from the ground, reflected on to the clouds.

他们在天空中看到的光可能是来自地面反射到云层上的光。

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Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or close to the ground—and at those levels the yellow-to-green wavelengths predominate.

在雨林中，很少有光透过树叶和树枝形成的树荫到达地面——或者接近地面——在这些高度上，黄色到绿色的波长占主导地位。

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When placed on the ground, baits should be situated on small paper cards or other flat, light-colored surfaces, or in test-tubes or vials.

诱饵放在地上时，应放在小纸卡上或其它平坦的浅色表面上，或放在试管或小瓶子里。

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During that era of rapid innovation, lives were sacrificed -- by test pilots in space and Gemini astronauts on the ground -- but the space program moved ahead at light speed.

CNN: Space is still the new frontier

Seen at ground level in early morning light, it can look beautiful--shimmering, lakelike, as if fish were swimming underneath its blue-white surface.

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