| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [verb] | 4562 |
|
| 2 | must have [vb pp] | 4527 |
|
| 3 | [modal v] have occurred | 148 |
|
| 4 | [vb mod] have occurred | 148 |
|
| 5 | must have occurred | 25 |
|
| 6 | must [verb] occurred | 25 |
|
| 7 | must have occur | 25 |
|
| 8 | must [vb infin] occurred | 25 |
|
| 9 | must have occurred | 25 |
|
