| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must be [vb pp] [prep] [be] [verb] | 17 |
|
| 2 | must be [vb pp] [prep] [be] [verb] | 17 |
|
| 3 | must be [vb pp] to [be] [verb] | 14 |
|
| 4 | must be [vb pp] to [be] [verb] | 14 |
|
