| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [vb pp] over a period | 16 |
|
| 2 | was [vb pp] over a period | 11 |
|
| 3 | is [vb pp] over a period | 6 |
|
| 4 | be made over a period | 5 |
|
