| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be difficult [to-vb] these | 17 |
|
| 2 | it be difficult [verb] these | 17 |
|
| 3 | it be difficult [verb] these | 17 |
|
| 4 | it is difficult [verb] these | 13 |
|
