義務之違反 債務不履行或未依債之本旨履行 補償無結果的費用 債務人遲延 締約時之給付不能 給付義務之排除 給付遲延 契約解除權 締約過失 情事變更原則 契約應遵守原則 不能之契約無效原則 Breach of duty Failure to perform or failure to perform properly Reimbursement for wasted expenditure Delay by the obligor Impediment to performance at the time of the conclusion of the contract Exclusion of the obligation to perform Delay in performance The right of termination Culpa in contrahando Clausula rebus sic stantibus Pacta sunt servanda Impossibilium nulla est obligatio