| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [prep] [det] [noun] | 16 |
|
| 2 | must have been [prep] [det] [noun sg] | 14 |
|
| 3 | must have been [prep] some [noun] | 6 |
|
| 4 | must have been [prep] this [noun] | 5 |
|
| 5 | must have been at [det] [noun] | 5 |
|
