| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must be [verb] [prep] [noun] | 1158 |
|
| 2 | [modal v] be [v-ing] [prep] [noun] | 944 |
|
| 3 | must [be] [v-ing] [prep] [noun] | 27 |
|
| 4 | must be [v-ing] [prep] [noun] | 27 |
|
| 5 | must [be] [v-ing] [prep] [noun] | 27 |
|
