| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | been [verb] [prep] a long period | 6 |
|
| 2 | [been] [verb] [prep] a long period | 6 |
|
| 3 | [been] [verb] over a long period | 5 |
|
| 4 | [been] [vb pp] [prep] a long period | 5 |
|
