As an important principle during the performance of contract, the substantial change of circumstance system is provided in continental law system and common law system countries.

情势变更原则作为合同履行的重要原则，在大陆法系及英美法系国家均有规定。

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The principle of the change of circumstance is one of the most important law principles in the contract of civil law.

情事变更原则是当代债法中最重要的法律原则之一。

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So the changed circumstance principle has become the important principle in numerous countries of world when dealing with the problem of the circumstance change.

因此，已成为当今世界上多数国家处理情势变更问题的重要原则。

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