| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | but it [vb mod] have been [prep] | 11 |
|
| 2 | but it [modal v] have been [prep] | 11 |
|
| 3 | but it could have been [prep] | 6 |
|
| 4 | but it could have been [prep] | 6 |
|
