履行不能是大陆法系债法上的重要概念，与迟延履行、不完全履行共同构成债务不履行的三大形态，是契约法上的核心问题之一。

Impossibility of performance, an important concept in the law of obligation in the Continent law System, is one of core questions in contract law.

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合同履行中的附随义务，是债法中的传统问题，在理论界偶有论述。

The incidental obligation in executing contracts, which is occasionally dealt with in the theory circle, is a traditional issue in the law of debt.

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