| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have [be] [v-ing] [prep] | 81 |
|
| 2 | [modal v] have [be] [v-ing] to | 38 |
|
| 3 | must have [be] [verb] to | 33 |
|
| 4 | must [verb] [be] [v-ing] to | 10 |
|
