| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [vb pp] [prep] a long period | 23 |
|
| 2 | [be] [vb pp] over a long period | 14 |
|
| 3 | [be] [vb pp] for a long period | 5 |
|
| 4 | been [vb pp] [prep] a long period | 5 |
|
| 5 | was [vb pp] [prep] a long period | 5 |
|
| 6 | [was/were] [vb pp] [prep] a long period | 5 |
|
| 7 | [been] [vb pp] [prep] a long period | 5 |
|
