| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been [vb pp] [prep] | 49363 |
|
| 2 | must have [vb pp] [prep] | 704 |
|
| 3 | must have been [vb pp] | 496 |
|
| 4 | must have been [prep] | 294 |
|
