They are not only strictly local but exhaustible; though, at a given place and time, they may exist in much greater abundance than would be applied to present use even if they could be obtained gratis.
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美
- 它们不仅严格地局限于某些地点,而且是可耗尽的,不过在某一地点和时间,即令可无偿得到它们,它们的储量也会远远超过所需的数量。