Likewise, as we're developing policies to try to encourage exports, if we know there's this externality -- this extra thing that's going to happen as we increase exports -- we can think about what the right kinds of policies are.
同样地 如果我们要出台鼓励出口的政策 我们知道有这样一种外部性 因为我们增加出口所带来的其他事情的变化 我们就可以更好的制定政策