| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] over a period [prep] | 76 |
|
| 2 | [verb] [adv] a period [prep] | 68 |
|
| 3 | [adv] over a period [prep] | 60 |
|
| 4 | [verb] [adv] over a period | 34 |
|
