B篇倒数第二段的倒数第二行The life expectancy of Japanese women has shot up to almost 85, the highest in the world.倒数第一段At the same time, extended families are being replaced by nuclear families.什么叫"extended families "，什么叫"nuclear families"?D,E两篇完全没有看懂，能否把大意说一下？
热心网友
nuclear families 指没有 grandparents 的家庭 其他的字典里有