As more and more of the known reserves of oil get used up, the present value of each barrel of the remaining oil begins to rise and, once more, exploration for additional oil becomes profitable.

随着越来越多的已知石油储量被耗尽，每桶剩余石油的现值开始上升，勘探更多石油再次变得有利。

In places such as San Diego, which has measly and brackish groundwater and currently imports 90% of its water, the answer must be greater conservation, as much reuse as possible, with most of the rest coming from the sea.

圣地亚哥拥有的地下水储量既少，盐份又高，如今其90%的用水需从外地引入。在像圣地亚哥这样的地方，其对策是尽能的节约用水、循环利用，而剩余不足的部份则大多从海洋中获取。