| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pron] must have been | 1980 |
|
| 2 | which [modal v] have been | 707 |
|
| 3 | [Wh det] must have been | 120 |
|
| 4 | which must have be | 64 |
|
| 5 | which must [verb] been | 64 |
|
| 6 | which must have been | 64 |
|
| 7 | which must have [been] | 64 |
|
| 8 | which must have [be] | 64 |
|
