| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adj] must have been [verb] | 18 |
|
| 2 | [adj] must have been [vb pp] | 17 |
|
| 3 | [det] must have been [verb] | 13 |
|
| 4 | this must have been [verb] | 8 |
|
| 5 | this must have been [verb] | 8 |
|
