| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [been] [adv] [prep] | 43 |
|
| 2 | must have [been] [adv] [prep] | 43 |
|
| 3 | [modal v] have [been] [adv] for | 25 |
|
| 4 | must have [been] [adv] for | 7 |
|
| 5 | must [verb] [been] [adv] for | 7 |
|
| 6 | must have [be] [adv] for | 7 |
|
