| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period of | 618 |
|
| 2 | [adv] [prep] a [adj] period | 124 |
|
| 3 | [adv] [prep] a period of | 87 |
|
| 4 | [adv] a [adj] period of | 20 |
|
| 5 | [adv] [prep] a [adj] of | 19 |
|
| 6 | [adv] [prep] [adj] period of | 11 |
|
