Old age in the United States presents many problems and opportunities. As a result of (36) medical services, people live longer than they used to. This (37) in longevity (寿命) creates a wide range of social needs. The medical (38) of gerontology (老年医学) opened up new (39) areas and careers related to the elderly. Because of changes in the family structure from (40) to nuclear, the elderly have to create (41) apart from basically small family units. This situation is (42) by the fact that many of their friends may have died and their children may have moved away. The elderly must set up a new life. Often, the elderly must rely on a fixed income--Social Security and (43) --and gradually diminished savings. (44) . However, the increasing proportion of elderly people in society has given them a new political power. (45) . Lobbying (游说) for such issues as increased Social Security benefits, better health care, income tax benefits and rent controls (46) .