| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [verb] been [vb pp] for | 18 |
|
| 2 | must [verb] be [vb pp] for | 18 |
|
| 3 | must have be [vb pp] for | 18 |
|
| 4 | must [vb infin] be [vb pp] for | 18 |
|
| 5 | must have be [vb pp] for | 18 |
|
