| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [modal v] have [been] [adv] | 2829 |
|
| 2 | must have [been] [adv] | 576 |
|
| 3 | must [verb] [been] [adv] | 535 |
|
| 4 | must have [be] [adv] | 535 |
|
