该书的最后几页的内容与历史无关，而是关乎未来 - 当我们面临水资源有限供给却依然过度消耗的时候，未来“灾难此起彼伏”。
The final few pages of the book are not about history but the future, where "cataclysm looms on every side" as we face a finite supply of water but a growing pattern of excessive use.
历史上，这一困难是通过设计一种把结构相关的部分与结构无关的部分分开的操作系统结构来克服的。
Historically, this difficulty has been addressed by developing an OS structure which separates the architecture specific and architecture size of its architecture specific parts of an OS.
而对于模型中与采集量历史记录无关、反映电压电流瞬时变化关系的元件则用实际元件模拟。
Those components of which values are independent on history record of sampled quantities and reflect the relationship of instantaneous voltage and current are realized by themselves.
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