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River deltas are difficult places for map makers .

河流三角洲对于地图编制者是个特殊的地方。

Deltas and diffs serve two distinct purposes , both of which are important .

增量和差别为两种不同的目的服务，它们都很重要。

Deltas will change over time as the relationship between the exercise price and underlying price changes .

对冲比率会随着时间因行使价及相关资产价格关系改变而改变。

It is one of the largest river deltas in the world , and currently protected as part of the yukon delta national wildlife refuge .

育空三角洲是全世界最大的三角洲之一，目前作为“育空三角洲国家生态保护区”而受到保护。

As cities on river deltas extract groundwater for industry , drinking and sanitation , the ground subsides , putting it further below sea level and thus requiring even higher dykes .

建在三角洲地段的城市抽取地下水为工业、饮用和卫生所用，土地下沉，离水平面更远因此需要更高的堤坝。