Economics is precise about the tax that should, in principle, be levied to deal with negative externalities: the tax on a liter of fuel should be equal to the harm caused by using a liter of fuel.

从经济学的角度来看，为了应对负外部性，原则上应该征收的税收是准确的：对一升燃料征收的税应该等于使用一升燃料所造成的危害。

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A liter of gas has less mass than a liter of water.

一公升气体的质量少于一公升水的质量。

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Our bodies can produces more than a liter of it every day. So what is it?

我们的身体每天能产生超过一升黏液。它是什么东西呢？

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"It's so simple. With a two-liter bottle you add sugar, you add extract, you add a small amount of yeast and water, cap it up and in two days they've got root beer.

VOA: special.2011.08.01

In an effort to battle Russia's rampant alcoholism, Russian President Dmitry Medvedev announced restrictions barring the sale of beer in cans or bottles larger than one-third of a liter.

VOA: standard.2009.10.15

It says that it will run for an hour on just a liter of water!

FORBES: Cars That Run On Air And Water

Four teenage girls figured out a way to use a liter of urine as fuel for generating six hours of electricity.

FORBES: Teens Create A Way To Use Urine As Fuel

With the help of many local governments, "A Liter of Light" and its collaborators have installed 12, 000 solar bottle bulbs, lighting 10, 000 homes in five Filipino provinces.

CNN: Plastic bottles light up lives