| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] [prep] [art] long period of | 30 |
|
| 2 | [vb pp] [prep] a long period of | 27 |
|
| 3 | [vb pp] [prep] a long period of | 27 |
|
| 4 | [vb pp] [prep] [art] long period of | 25 |
|
| 5 | [vb pp] over [art] long period of | 14 |
|
| 6 | [vb pp] for [art] long period of | 6 |
|
