| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adj] period of time | 319 |
|
| 2 | [adv] [adj] period of time | 57 |
|
| 3 | [adv] a [adj] period of | 20 |
|
| 4 | [adv] a period of time | 5 |
|
