| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | been [vb pp] [prep] a period | 25 |
|
| 2 | been [vb pp] [prep] a period | 25 |
|
| 3 | been [vb pp] by a period | 6 |
|
| 4 | been [vb pp] by a period | 6 |
|
| 5 | been [vb pp] in a period | 5 |
|
| 6 | been [vb pp] in a period | 5 |
|
