| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a longer period [prep] [noun] | 12 |
|
| 2 | [prep] a longer period [prep] [noun] | 12 |
|
| 3 | over a longer period [prep] [noun] | 6 |
|
| 4 | over a longer period [prep] [noun] | 6 |
|
