This is extremely important, because it determines how fast and at what light sensitivity (ISO) your camera can shoot in different lighting conditions.

光圈非常重要，因为它决定你的相机在不同照明条件下拍摄速度有多快，以及拍摄时的感光度(iso)为多少。

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With recent advances in technology over the past several years, many groups of scientists have been investigating exactly how fast light can travel.

随着过去几年间技术上的进步，许多科学家团队都进行了精细的研究来验证光速。

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At the root of this strange time warping effect lies Einstein's postulate that the speed of light should be the same for all observers, no matter how fast they are moving.

实际上，根据爱因斯坦假设的时间隧道效应，光速在所有观察者眼中是不变的，无论他们移动的多快。

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Shining an appropriate light on such a wire from the outside would alter its refractive index (a measure of how fast light travelling inside the wire can move).

ECONOMIST: New-age crystals

Astrophysicists can determine how the blazar grew brighter in different parts of the spectrum at different times and refine their models of how fast-moving particles within the jets give rise to the high-energy light.

BBC: Blazar Markarian 421's flare-up is cosmic coincidence