| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [prep] | 289 |
|
| 2 | must have been [prep] | 289 |
|
| 3 | [modal v] have been for | 62 |
|
| 4 | must have been for | 14 |
|
| 5 | must [verb] been for | 14 |
|
| 6 | must have been for | 14 |
|
| 7 | must [vb infin] been for | 14 |
|
| 8 | must have [be] for | 14 |
|
| 9 | must have be for | 14 |
|
| 10 | must have [been] for | 14 |
|
