| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period of | 544 |
|
| 2 | [vb pp] [prep] a [adj] period | 266 |
|
| 3 | [vb pp] [prep] a period of | 215 |
|
| 4 | [vb pp] [prep] a [adj] of | 43 |
|
| 5 | [vb pp] [prep] [adj] period of | 18 |
|
| 6 | [vb pp] a [adj] period of | 15 |
|
