| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] [adv] a period of | 7 |
|
| 2 | [is] [adv] a period of | 7 |
|
| 3 | is [adv] a period of | 7 |
|
| 4 | [is] [adv] a period of | 6 |
|
