| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | this [vb mod] have been | 406 |
|
| 2 | this may have been | 129 |
|
| 3 | this would have been | 112 |
|
| 4 | this could have been | 51 |
|
| 5 | this might have been | 42 |
|
| 6 | this must have been | 42 |
|
| 7 | this should have been | 21 |
|
| 8 | this will have been | 9 |
|
