| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [been] [verb] [prep] | 320 |
|
| 2 | must have [been] [verb] [prep] | 320 |
|
| 3 | [modal v] have [been] [verb] for | 290 |
|
| 4 | must [verb] [been] [verb] for | 36 |
|
| 5 | must have [been] [verb] for | 36 |
|
| 6 | must have [be] [verb] for | 36 |
|
