次の語彙は、要チェックです。respresent 13%, by 2025, elderly, currently, be referred to as, graying of America, demographic change, factors, fertility, mortality, immigration, in large part, influence, be no exception, large segment, birth rate, death rate, significant, medical advances, life expectancy, antibiotics, drug therapies, surgical techniques, a significant contritubion, devices for diagnosis, treatment, extend lives, whereas, retirement age, be projected to.., contribute to, massive immigration, of child-bearing age, encourage