| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [verb] seen [det] | 12 |
|
| 2 | must have seen [det] | 12 |
|
| 3 | must have seen [det] | 12 |
|
| 4 | must [vb infin] seen [det] | 12 |
|
