Legal analysis: As a complete contract, it should be true in content, complete in expression, clear in agreement, standard in page and error-free. Generally speaking, the contents of a contract are not allowed to be changed. A contract with altered marks must be confirmed by the parties to the contract as an act of contract agreement, otherwise the altered contract will be regarded as invalid or partially invalid.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 543 The parties may modify the contract through consultation.

Article 544 Where the parties have not expressly agreed on the contents of the contract modification, it is presumed that the contract has not been modified.

Article 490 Where the parties conclude a contract in the form of a contract, the contract is formed when the parties sign, seal or fingerprint it. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it.