| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [vb infin] been [verb] [prep] | 320 |
|
| 2 | [modal v] [vb infin] been [v-ing] [prep] | 287 |
|
| 3 | [vb mod] [vb infin] been [v-ing] [prep] | 287 |
|
| 4 | must [vb infin] [be] [v-ing] [prep] | 81 |
|
| 5 | must [vb infin] been [v-ing] [prep] | 81 |
|
| 6 | must [vb infin] be [v-ing] [prep] | 81 |
|
| 7 | must [verb] been [v-ing] [prep] | 81 |
|
| 8 | must [vb infin] [been] [v-ing] [prep] | 81 |
|
