How many groups can people be divided into?They can be dividen into ______ group

People work for a number of reasons, and they can be divided into two main groups. One is those who work out of necessity, and the other is those who work to dispose of free time. Most people are not independently wealthy, so they work in order to support themselves or their family. Others have a job in order to have something to do with their time. Many men and women find retirement boring. They take part-time jobs. In some families, the children have left home, then the mothers often get jobs to kill their free time.
    Studies show that the ability to use free time does not come naturally; it is a skill that has to be learned.