Aging poses a serious challenge to OECD(Organization of Economic Co-operation and Development)countries，in particular，how to pay for future public pension liabilities. And early retirement places an__1__burden on pension financing. There is no easy solution，but__2__retirement could help. Early retirement may seem like a worthy individual goal，but it is a socially__3__one，and makes the present public pension system difficult to sustain for long. The__4__reason is that more people are retiring early and living longer. That means more retirees depending on the__5__of those in work for their income. The__6__is worrying. In the next 50 years，low fertility rates and__7__life expectancy in OEC
