| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | occur over [art] period | 7 |
|
| 2 | occur [adv] [art] period | 7 |
|
| 3 | occur [adv] [art] period | 7 |
|
| 4 | occur over [art] period | 7 |
|
| 5 | occur [adv prt] [art] period | 7 |
|
| 6 | occur [adv] a period | 6 |
|
| 7 | occur [adv] a period | 6 |
|
