| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] over a period [prep] | 71 |
|
| 2 | [adv] over a period [prep] | 60 |
|
| 3 | [adv] [vb pp] a period [prep] | 13 |
|
| 4 | [adv] [vb pp] over a period | 8 |
|
