| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [be] [verb] on a | 28 |
|
| 2 | must [be] [vb pp] on a | 28 |
|
| 3 | must be [verb] on a | 28 |
|
| 4 | must be [verb] on a | 28 |
|
| 5 | must [be] base on a | 11 |
|
| 6 | must [be] based on a | 11 |
|
