| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [vb pp] for [adj] | 5 |
|
| 2 | must [vb infin] been [vb pp] for [adj] | 5 |
|
| 3 | must [vb infin] been [vb pp] for [adj] | 5 |
|
