More formally, sets contain no pair of elements e1 and e2 such that e1.equals (e2), and at most one null element.

更准确地说，set不包含成对的e1和e2元素，因此如果e1 . equals (e2)，那么最多包含一个null元素。

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Adding elements to the map is a little more involved than adding to a set, only because we have to put each pair of elements separately.

向映射表添加元素要比向集添加元素更加棘手一些，只是因为我们不得不单独put每一对元素。

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Supercomputers have huge storage capacity and can operate in parallel on corresponding elements of arrays of Numbers rather than on one pair of elements at a time.

超级计算机具有巨大的贮存容量，能够同时处理大批的数字元素而不是每次处理一对元素。

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Tyler Hays is the founder of the upscale brand BDDW, whose Philadelphia woodworkers and metalsmiths pair muscular wood elements with wabi-sabi bronze pedestals and casework.

WSJ: The New American Minimalism