1. Establish a sinking fund to repay the principal and interest of the debt. Annual sinking fund = final value of annuity × sinking fund coefficient of installment bonds.

2. Set the maturity dates of all bonds at different times.

3. Repay the principal and interest of the same bond in installments, and pay off the principal and interest on the maturity date of the bond at the time of redemption.

4. Redeem at any time

5. Deferred redemption

6, converted into common stock

7. Issue new bonds to replace the old ones.