| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] over a period of [noun sg] | 9 |
|
| 2 | [adv] over a period [prep] [noun sg] | 9 |
|
| 3 | [adv] over a period [prep] time | 9 |
|
| 4 | [adv] over a period of [noun sg] | 9 |
|
