| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adj] period of | 842 |
|
| 2 | [adv prt] a [adj] period | 76 |
|
| 3 | [adv prt] a period of | 67 |
|
| 4 | [adv prt] a [adj] of | 36 |
|
