[音频]The treatment of the elderly can be further (1)___________ by distinguishing between nuclear and extended family structures. In the United States the nuclear family, which (2) ________ of the father, the mother, the children, is considered " the family". The extended family, common in other cultures, (3) __________ grandparents, aunts, uncles, cousins, nephews, nieces, and in-laws. The distinction between the nuclear and extended family is (4) __________ because it (5)_________ the extent of family ties and obligations. In extended families the children and parents have strong ties and obligations to relatives. It is common in these families to support older family members, to have intensive contact with relatives, and to (6) _____________ communal housing.The American nuclear family usually has its own separate residence and is economically independent of other family members. Relatives are still considered "family" but are often outside the (7) _______ obligations that people have to their immediate families. When couples (8) _______, they are expected to live independently of their parents and become "heads of (9)____________" when they have children. It is not unusual in times of (10)___________ need for nuclear family members to borrow money from a (11)____________ rather than from relatives. Grandparents, aunts, uncles, and cousins, then, are not directly (12)______________ in the same way as they would be in an extended family structure.