| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun] over a period of | 289 |
|
| 2 | [noun] over a [adj] period | 262 |
|
| 3 | over a [adj] period of | 128 |
|
| 4 | [noun] a [adj] period of | 6 |
|
