| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] a [adj] period of | 116 |
|
| 2 | [verb] by a period of | 29 |
|
| 3 | [verb] by a [adj] period | 14 |
|
| 4 | by a [adj] period of | 10 |
|
