He didn't flip on the headlights until he was two blocks away.

直到过了两个街区后，他才打开前灯。

《柯林斯英汉双解大词典》

If you're in a vehicle going the speed of light, what happens when you turn on the headlights?

如果你开著以光速行进的车，打开车灯的时候会发生什么事？

youdao

Turn on the headlights, she repeated, and without waiting for a response she leaned over and did it herself.

把前灯打开，她重复道，没等我的答复她就侧过身来自己打开了前车灯。

youdao

Elliot started the engine, turned on the headlights and the windshield wipers.

NEWYORKER: Another Manhattan

This scenario is commonly referred to as 'head-lighting' because it looks like the dark space on the road between the headlights of a car.

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Now, at the closing speed, the headlights on, I would've had a hard time telling the color of the vehicle, let alone the driver.

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