the credit card balance is the spending limit you have generated. \xd\ For example, if your available line is 1, yuan and you spend 1 yuan, then this 1 yuan is your balance, and the remaining 9, yuan is the available line. \xd\ If you deposit it in 1 yuan, your balance is -1 yuan, and the available line is 11, yuan. \xd\ Therefore, when the balance is positive, it needs to be repaid; when it is negative, it means that you have overpaid and need not repay.