| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a longer period | 86 |
|
| 2 | over a longer period | 51 |
|
| 3 | over a longer period | 51 |
|
| 4 | for a longer period | 30 |
|
| 5 | for a longer period | 30 |
|
