The quantity that revokable contracts is relatively large in legal practice, affirmation of revocable contracts is relatively complicated, the contracts 'change and revoke can produce important influence to the contract parts and third person. 在司法实践中,可撤销合同的数量比较大,认定情况也比较复杂,合同的变更或撤销,对当事人甚至第三人的利益都会产生重要影响。