| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] [adv] a period of | 67 |
|
| 2 | occur [adv] a [noun sg] of | 6 |
|
| 3 | occur [adv] a [noun] of | 6 |
|
| 4 | occur [adv] [art] period of | 6 |
|
| 5 | occur [adv] [art] period of | 6 |
|
| 6 | occur [adv] a period [prep] | 5 |
|
| 7 | occur [adv] a period of | 5 |
|
| 8 | occur [adv] a period of | 5 |
|
