| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [adv] [prep] | 23 |
|
| 2 | [modal v] have been [adv] for | 22 |
|
| 3 | must have been [adv] for | 7 |
|
| 4 | must have be [adv] for | 6 |
|
| 5 | must have [been] [adv] for | 6 |
|
| 6 | must have [be] [adv] for | 6 |
|
| 7 | must [verb] been [adv] for | 6 |
|
