答：有效，除非约定合同生效需签字并盖章。
Answer: effective, unless the contract agreed to sign and seal.
本合同自甲方盖章、乙方签署之日起生效。 。
This contract shall come into effect since both sides sign their names.
本翕合同只能按照双方授权代表签名盖章的文件进行修改或增补；
This Contract can only be altered, amended or supplemented in accordance with documents signed and sealed by authorized representatives of both parties.
应用推荐