| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it must have been [adj] | 156 |
|
| 2 | it have been [prep] [adj] | 116 |
|
| 3 | it must have been [prep] | 83 |
|
| 4 | must have been [prep] [adj] | 51 |
|
