| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [be] [verb] | 12068 |
|
| 2 | must [be] [vb pp] | 11030 |
|
| 3 | [modal v] [be] used | 6356 |
|
| 4 | [vb mod] [be] used | 6356 |
|
| 5 | must [be] use | 163 |
|
| 6 | must [be] used | 158 |
|
