| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] over a period | 39 |
|
| 2 | [adv] for a period | 28 |
|
| 3 | [adv] after a period | 17 |
|
| 4 | [adv] in a period | 13 |
|
| 5 | gradually [prep] a period | 7 |
|
| 6 | only [prep] a period | 7 |
|
| 7 | [adv] during a period | 6 |
|
| 8 | especially [prep] a period | 5 |
|
| 9 | even [prep] a period | 5 |
|
