[单项选择]

Marriage is still a popular institution in the United States, but divorce is becoming almost as "popular". Most American people get married, but at the present time, fifty percent of American marriages end up in divorce. However four out of five divorced people do not stay single. They get marriages a second time to new partners. Sociologists tell us that in the next century, most American people will many three or four times in one lifetime. Alvin Toffler, an American sociologist, calls this new social form serial marriages. In his book Future Shock, Toffler gives many reasons for this change in American marriage. In modern society, people’ s lives don’ t stay the same for very long. Americans frequently change their jobs, their homes, and their circle of friends. So the person who was a good husband or wife ten years ago is sometimes not as good ten years later. After some years of marriage, a husband or wife can feel that their lives have become v
A. A social practice.
B. A social organization.
C. A state law.
D. An established habit.

Marriage is still a popular institution in the United States, but divorce is becoming almost as "popular". Most American people get married, but at the present time, fifty percent of American marriages end up in divorce. However four out of five divorced people do not stay single. They get marriages a second time to new partners. Sociologists tell us that in the next century, most American people will many three or four times in one lifetime. Alvin Toffler, an American sociologist, calls this new social form serial marriages. In his book Future Shock, Toffler gives many reasons for this change in American marriage. In modern society, people’ s lives don’ t stay the same for very long. Americans frequently change their jobs, their homes, and their circle of friends. So the person who was a good husband or wife ten years ago is sometimes not as good ten years later. After some years of marriage, a husband or wife can feel that their lives have become v
A. difference in interests
B. difference in age
C. difference in family background
D. difference in choosing jobs