| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [verb] [been] for | 14 |
|
| 2 | must have [been] for | 14 |
|
| 3 | must [vb infin] [been] for | 14 |
|
| 4 | must [verb] been for | 14 |
|
| 5 | must have [been] for | 14 |
|
