During the next ten years, the situation changed. There were fewer divorces, and people married at a younger age and had more children than the previous generation. It was unusual for a mother to work outside the home during the years when her children were growing tip. Families began leaving cities and moving into single-family homes in the suburbs. The traditional family seemed to be returning. 　　In the years between 1960s and 1990s, there were many important changes in the structure of the family. From the 1960s to the early 1970s, the divorce rate doubled and the birthrate fell by half. The number of single-parent families tripled, and the number of couples living together without being married doubled again. In fact, the single-parent household, once unusual, has replaced the traditional family as the typical family in the States. If we can judge from history, however, this will probably change again in the twenty-first century. 　　The Changes of the American Family Main comparisons Contexts Different___1____ There were two __2___ types of families in the past, ___3____, the extended and the nuclear. Nowadays __4___types of families can be seen than before.