| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [prep] [noun sg] | 25 |
|
| 2 | must [vb infin] been [prep] [noun sg] | 25 |
|
| 3 | must have been [prep] [noun sg] | 25 |
|
| 4 | must [verb] been [prep] [noun sg] | 25 |
|
| 5 | must [verb] been in [noun sg] | 17 |
|
