| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] longer period of | 9 |
|
| 2 | [prep] longer periods of | 9 |
|
| 3 | [prep] longer period of | 9 |
|
| 4 | for longer period of | 8 |
|
| 5 | for longer period of | 8 |
|
