원고 회사가 피고들에게 위 각 약속어음을 반환할 수 없게 되었으므로, 원고 회사의 피고들에 대한 공사대금 채권은 소멸되었다.
As the Plaintiff Company was unable to return each of the promissory notes to the Defendants, the Plaintiff's bond against the Defendants was extinguished.