The best professionals account for this with smart, defensive design strategies (also known as contingency design).

最好的职业人士靠聪明的防护性设计策略来对此负责(亦被称为权变设计)。

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However, in advance of project completion, the source of contingency expenses is not known.

然而，在项目完工前，应急储备金的动用与否是根据意外事件是否发生来确定的。

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