| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [vb infin] been [verb] | 793 |
|
| 2 | [vb infin] been [verb] in | 645 |
|
| 3 | must [vb infin] [verb] in | 123 |
|
| 4 | must [vb infin] been in | 89 |
|
