Legal analysis: the main contract is a contract that can exist independently without the premise of other contracts. This contract is independent. Subordinate contract, also known as subsidiary contract, is a contract based on the existence of other contracts. Guarantee contract, deposit contract, pledge contract, etc. It is a subsidiary contract of the loan contract that provides guarantee. The existence of the slave contract is based on the existence of the master contract, so the establishment and effectiveness of the master contract directly affects the establishment and effectiveness of the slave contract. However, the establishment and entry into force of the subordinate contract does not affect the establishment and entry into force of the main contract.

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

Article 675 The borrower shall repay the loan within the agreed time limit. If there is no agreement or unclear agreement on the loan term, and it cannot be determined according to the provisions of Article 510 of this Law, the borrower may return it at any time, or may urge the borrower to return it within a reasonable period.

Article 676 If the borrower fails to repay the loan within the agreed time limit, it shall pay the overdue interest in accordance with the agreement or the relevant provisions of the state.

Article 677 Where the borrower repays the loan in advance, unless otherwise agreed by the parties, the interest shall be calculated according to the actual loan period.

Article 678 The borrower may apply to the lender for an extension before the repayment period expires, and the extension may be extended with the consent of the lender.

Article 679 A loan contract between natural persons is established when the lender provides the loan.