A contract is invalid, but an agreement is valid.
 Because there must be more than two contracts, the agreement or anything else can be unilateral. If there are several parties to a contract, there must be at least several copies of the contract, one for each party. If it is in quadruplicate, it is reasonable for Party A to hold three copies and Party B to hold one copy, which does not violate the provisions of the Contract Law.
 Civil Code
 Article 153 A civil juristic act that violates the mandatory provisions of laws and administrative regulations is invalid. However, the exception is that the mandatory provisions do not invalidate the civil juristic act. Civil juristic acts violating public order and good customs are invalid.
 Article 146 A civil juristic act performed by the actor and the counterpart with a false declaration of intention is invalid. The validity of a civil juristic act concealed by a false declaration of intention shall be dealt with in accordance with the provisions of relevant laws.
 Article 490 Time of Formation: Where the parties entered into a contract in the form of a written contract, the contract was formed when all the parties signed, sealed or fingerprinted it. The contract is formed when one party has performed its main obligations and the other party has accepted them before signing, sealing or fingerprinting.
 A contract shall be concluded in writing as required by laws and administrative regulations or as agreed by the parties. A contract is formed when the parties fail to adopt a written form but one party has performed its main obligations and the other party has accepted it.