| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] [adv] over a period of | 16 |
|
| 2 | [vb pp] [adv] over a period [prep] | 16 |
|
| 3 | [vb pp] [adv] over a period of | 16 |
|
| 4 | [vb pp] [adv prt] over a period [prep] | 12 |
|
