第一部分是履行不能概述，这是本文进行研究的理论前提。

Part I is introduction of impossibility of performance, and it's the theoretical precondition of the research.

youdao

第一部分是履行不能概述，这是本文进行研究的理论前提。

Part I is introduction of impossibility of performance, and it's the theoretical precondition of the research.

youdao