| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | what it must have been [prep] | 13 |
|
| 2 | what it must [verb] been [prep] | 13 |
|
| 3 | what it must [verb] been like | 13 |
|
| 4 | what it must have been [prep] | 13 |
|
| 5 | what it must [vb infin] been [prep] | 13 |
|
| 6 | what it must [verb] been [prep] | 13 |
|
