| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb infin] [prep] a [adj] period of | 11 |
|
| 2 | [vb infin] [prep] a [adj] period of | 11 |
|
| 3 | [vb infin] [prep] a [adj] period of | 10 |
|
| 4 | [vb infin] for a [adj] period of | 8 |
|
| 5 | [vb infin] for a [adj] period of | 8 |
|
