| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [be] [verb] back [prep] the | 9 |
|
| 2 | must be [verb] back [prep] the | 9 |
|
| 3 | must [be] [vb pp] back [prep] the | 9 |
|
| 4 | must [be] [verb] back to the | 5 |
|
