From the traditional "four generations under one roof" to the current "three families", the structure of the family is constantly evolving, and now the general type of family structure is (

Test Question Analysis: The nuclear family refers to a family consisting of a husband and wife and their children, and **** living under the same roof. Main family, a family pattern in which parents and a pair of married children live together. It usually includes three generations of immediate family members such as grandparents, parents and unmarried children. Therefore, the evolution from the traditional "four generations living together" to the current "three families" is the evolution of the main family to the nuclear family. Nowadays, the general structure of the family is the nuclear family and the main family, choose A.