| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [been] a [noun] [prep] | 81 |
|
| 2 | [modal v] have [been] a [noun] for | 39 |
|
| 3 | [vb mod] have [been] a [noun] for | 39 |
|
| 4 | must have [been] [art] [noun] for | 13 |
|
| 5 | must have [been] a [noun] for | 9 |
|
| 6 | must have [be] a [noun] for | 9 |
|
| 7 | must [verb] [been] a [noun] for | 9 |
|
