| 1 | Autor finds that job growth divides neatly into three categories. | |
| 2 | Jealousy can be best divided into two main categories: normal and abnormal. | |
| 3 | He found that, as a rule, people fall into one of three broad categories of beliefs concerning pets. | |
| 4 | Apple requires developers to put their app into one of 20 categories. | |
| 5 | They then grouped the participants into two categories: those who use social networks and those who don't. |