| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [been] [adj] | 750 |
|
| 2 | [modal v] have [been] [det] | 361 |
|
| 3 | must [verb] [been] [det] | 93 |
|
| 4 | must have [been] [det] | 93 |
|
| 5 | must [vb infin] [been] [det] | 93 |
|
| 6 | must have [be] [det] | 92 |
|
