| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [verb] [be] [v-ing] [prep] | 135 |
|
| 2 | it must [verb] [be] [prep] | 83 |
|
| 3 | must [verb] [be] [v-ing] [prep] | 81 |
|
| 4 | it must [verb] [be] [v-ing] | 22 |
|
| 5 | it must [be] [v-ing] [prep] | 10 |
|
