| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which have been [verb] in a | 26 |
|
| 2 | which have been [vb pp] in a | 25 |
|
| 3 | which had been [verb] in a | 16 |
|
| 4 | which has been [verb] in a | 7 |
|
