| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [det] must have [been] [verb] [prep] | 7 |
|
| 2 | [det] must have been [verb] [prep] | 7 |
|
| 3 | [det] must have [been] [vb pp] [prep] | 7 |
|
| 4 | this must have [been] [verb] [prep] | 5 |
|
