我可以相当准确地说出这件事发生的时间。
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。
Before presenting some examples, it is worth being precise about some nomenclature.在举例之前,明确一些术语是非常有意义的。