Light travels basically a foot in a nanosecond. Simple rule of thumb.

光行进的速度是每纳秒一英尺，很简单的经验法则了。

youdao

In the pale light of the tunnel, 30-foot fossil traces of lycopsid gleam slickly in the shale roof like alligator skins.

在隧道内黯淡的灯光下，页岩顶部30英尺长的石松化石遗迹就像鳄鱼皮般发出柔滑的光亮。

youdao

Find out your plant’s foot-candle requirement, which is how many candles it would take to light the plant from one foot away.

找出植物所需要的“英尺烛光”，即在一英尺的距离需要点多少蜡烛来提供它光。

youdao

Someone else who questions the light foot-print theory is David Rhode.

BBC: Is Obama's drone doctrine counter-productive?

He believes that they kill America's enemies with minimum risk to the innocent and are a "light foot-print" compared to the heavy boot of invasion and occupation.

BBC: Is Obama's drone doctrine counter-productive?

He says that is not a light foot-print.

BBC: Is Obama's drone doctrine counter-productive?