用桔黄烟雾信号以识别。

Make identification with orange smoke signals.

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为什么交通信号灯采用红、黄、绿色？

Why are stoplights Red, Yellow and Green?

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每一方向都有红、黄、绿组成的交通信号灯。

Each direction has a red, yellow, green, composed of traffic lights.

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每一方向都有红、黄、绿组成的交通信号灯。

Each direction has a red, yellow, green, composed of traffic lights.

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