Article 29 The general contractor of a construction project may subcontract part of the contracted project to a subcontracting unit with corresponding qualifications; however, in addition to the subcontracting agreed in the general contracting contract, it must Approved by the construction unit. For general construction contracting, the construction of the main structure of the construction project must be completed by the general contractor itself.

The general contractor of a construction project shall be responsible to the construction unit in accordance with the provisions of the general contract; the subcontracting unit shall be responsible to the general contractor in accordance with the provisions of the subcontract. The general contractor and the subcontractor shall be jointly and severally liable to the construction unit for the subcontracted project

- "Construction Law"

Article 3 Economic contracts, except those that are settled immediately, It should be in writing. The documents, telegrams and diagrams concerning the modification of the contract agreed upon by the parties are also an integral part of the contract.

——"Economic Contract Law"