During the late seventies world grain reserves were rebuilt . 七十年代末，世界粮食储备重新建立。
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This comes at a time when world grain stocks are at their lowest level in 30 years and when u . s . farmers are losing irrigation water to aquifer depletion and to cities 这种大规模的采购适逢世界粮食储备正处于30年来的最低水平，以及美国的农民由于蓄水层枯竭和城市用水正在失去他们的灌溉用水。
