| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] a [adj] period [prep] | 27 |
|
| 2 | [adv] a [adj] period [prep] | 27 |
|
| 3 | [adv] a [adj] period of | 20 |
|
| 4 | [adv] a [adj] period of | 20 |
|
| 5 | only a [adj] period [prep] | 14 |
|
| 6 | [adv] a short period [prep] | 10 |
|
| 7 | [adv] a short period [prep] | 10 |
|
