Relativity says that light always moves in a straight line through empty space, and always at the same speed in a vacuum, no matter what your observation point.

它指出光在真空中走直线，且在真空中光速恒定，不论你的观测点如何。

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For high-speed and low-drive -power light, modulation, the advantages of the use of asymmetric strip line was shown.

对结果的分析讨论表明，非对称微带电极用于极性反转电极结构对在高频波段实现低驱动功率光调制是十分有效的。

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It is applied for the special line with steep gradient and small radius of curvature. This tourist car which runs with light load and low speed has high safe ty performance.

这是一种用于旅游胜地的新型环保车，适用于大坡道、小曲率半径的特殊线路，轻载低速，安全性能高。

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