| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [to-vb] a [adj] period [prep] | 25 |
|
| 2 | [to-vb] a [adj] period [prep] | 23 |
|
| 3 | [to-vb] a [adj] period [prep] | 19 |
|
| 4 | [to-vb] a [adj] period of | 19 |
|
| 5 | [to-vb] a [adj] period of | 19 |
|
| 6 | [to-vb] a [adj -er] period [prep] | 6 |
|
