| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] over a [adj] period [prep] | 24 |
|
| 2 | [vb pp] over a [adj] period of | 23 |
|
| 3 | [vb pp] over a long period [prep] | 16 |
|
| 4 | [vb pp] over a long period [prep] | 13 |
|
