| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [vb pp] over a period | 16 |
|
| 2 | be [vb pp] for a period | 15 |
|
| 3 | be [vb pp] within a period | 10 |
|
| 4 | be [vb pp] as a period | 6 |
|
| 5 | be [vb pp] by a period | 5 |
|
