| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must be [verb] [prep] | 5095 |
|
| 2 | must be [vb pp] [prep] | 4919 |
|
| 3 | [modal v] be referred [prep] | 264 |
|
| 4 | [vb mod] be referred [prep] | 264 |
|
| 5 | must be refer [prep] | 24 |
|
| 6 | must be referred [prep] | 20 |
|
| 7 | must [be] referred [prep] | 20 |
|
| 8 | must be referred [prep] | 20 |
|
| 9 | must be referred [prep] | 20 |
|
| 10 | must [be] referred [prep] | 20 |
|
