| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it must be [prep] | 189 |
|
| 2 | it be [prep] [to-vb] | 99 |
|
| 3 | must be [prep] [to-vb] | 9 |
|
| 4 | it must be [to-vb] | 9 |
|
