| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb infin] [verb] a [adj] period [prep] | 6 |
|
| 2 | [vb infin] [to-vb] a [adj] period [prep] | 5 |
|
| 3 | [vb infin] [verb] a [adj] period of | 5 |
|
