| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have be [verb] [prep] | 320 |
|
| 2 | [modal v] have be [v-ing] [prep] | 288 |
|
| 3 | must [verb] be [v-ing] [prep] | 81 |
|
| 4 | must have [be] [v-ing] [prep] | 81 |
|
