You must turn on your vehicle headlights if you cannot clearly see a person or vehicle how many metres away?

不能清楚看見多少米外的人或車輛時，必須開啓汽車頭燈？

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Also use a speed allowing safe stopping within the applicable visible distance. Dip in fog; reflected high beam can worsen visibility.

應同時降低到可在視線內安全停住的速度；霧中使用近光，遠光反射可能令視線更差。