| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must be [verb] to | 714 |
|
| 2 | must be [vb pp] to | 682 |
|
| 3 | [vb mod] be referred to | 246 |
|
| 4 | [modal v] be referred to | 246 |
|
| 5 | must be refer to | 21 |
|
| 6 | must be referred [prep] | 20 |
|
| 7 | must be referred [prep] | 20 |
|
| 8 | must [be] referred to | 17 |
|
| 9 | must [be] referred to | 17 |
|
| 10 | must be referred to | 17 |
|
| 11 | must be referred to | 17 |
|
| 12 | must be referred to | 17 |
|
