| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv prt] [art] period of | 70 |
|
| 2 | [adv prt] a period of | 67 |
|
| 3 | [adv prt] a period of | 67 |
|
| 4 | over [art] period of | 63 |
|
