| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pron] must have [been] | 1937 |
|
| 2 | [pron] must have [det] | 132 |
|
| 3 | must have [been] [det] | 92 |
|
| 4 | [pron] have [been] [det] | 7 |
|
