| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it must [be] [vb pp] | 1391 |
|
| 2 | must [adv] [be] [vb pp] | 996 |
|
| 3 | it must [adv] [be] | 222 |
|
| 4 | it [adv] [be] [vb pp] | 123 |
|
