| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | but he must have been | 12 |
|
| 2 | but he must [verb] been | 12 |
|
| 3 | but he must [verb] been | 12 |
|
| 4 | but he must have been | 12 |
|
| 5 | but he must [verb] been | 12 |
|
| 6 | but he must [vb infin] been | 12 |
|
