| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be difficult [prep] [indef pn] | 11 |
|
| 2 | be difficult [prep] [indef pn] [to-vb] | 10 |
|
| 3 | it be [prep] [indef pn] [to-vb] | 5 |
|
