递归在haskell中至关重要。 与命令式语言要求你去表达求解的方式不同，haskell更倾向于让你提供问题的描述。

Recursion is important to Haskell because unlike imperative languages, you do computations in Haskell by declaring what something is instead of declaring how you get it.

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全国大约有四百个城市的市场签署一项无约束力的行政命令要求减少他们城市的温室气体排放，旨在与京都议定书接轨。

Almost 400 mayors around the country have signed a non-binding agreement to reduce their cities’ emissions in keeping with the Kyoto Protocol.

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要求提高认识，规范“双向代职”制度，把“双向代职”与“职称评定”挂钩，变行政命令为自觉行动；

We should improve consciousness, regulate the system of mutual agency duty, link the system with promotion, and change the situation of obeying administrational orders into voluntary actions.

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