| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [verb] the [noun sg] | 7 |
|
| 2 | must have been [verb] the [noun sg] | 7 |
|
| 3 | must have been [verb] the [noun sg] | 7 |
|
| 4 | must have been [v-ing] the [noun sg] | 6 |
|
