In the case of the ambulance and police car, it's more a question of brightness.

警车和救护车上之所以用红灯，大多是因为红灯亮度大。

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And I could take that information, type it up into a program, make some assumptions about speed and direction and what routes they're going to take and actually watch the ambulance go to St. John's Mercy.

我得到这条信息之后，将它输入程序里，假设它们的速度和方向,以及它们应走哪条线路,就能看到救护车进入圣约翰医院。

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