| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [verb] been at [det] [noun sg] | 5 |
|
| 2 | must have been at [det] [noun] | 5 |
|
| 3 | must [verb] been at [det] [noun] | 5 |
|
| 4 | must have been at [det] [noun] | 5 |
|
| 5 | must [vb infin] been at [det] [noun] | 5 |
|
