| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adj] period of | 842 |
|
| 2 | a [adv] [adj] period | 267 |
|
| 3 | [adv] [adj] period of | 156 |
|
| 4 | a [adv] [adj] of | 144 |
|
