| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [been] [det] [noun] | 49 |
|
| 2 | it must have [been] [noun] | 39 |
|
| 3 | it must have [been] [det] | 25 |
|
| 4 | it must have [det] [noun] | 5 |
|
