| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] a [adj] period of | 131 |
|
| 2 | to a [adj] period of | 18 |
|
| 3 | [verb] to a period of | 14 |
|
| 4 | [verb] to a [adj] period | 10 |
|
