Pay-as-you-go pension systems, for example, depend on there being enough workers to fund promises made to retired employees.
举例来说，现收现付养老金体制依靠国家要有足够的工人，才能维持承诺，为退休的雇员提供资金来源。
2
Retired people at first pay nothing; accumulated interest and all fees are paid off when the home is sold, with any excess equity going to the homeowner's heirs.