| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] over a [adj] period of | 23 |
|
| 2 | [vb pp] over a [adj] period of | 21 |
|
| 3 | [vb pp] over a long period of | 14 |
|
| 4 | [vb pp] over a long period of | 12 |
|
