| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [coord] it [is] difficult [to-vb] [subord] | 7 |
|
| 2 | [coord] it is difficult [verb] [subord] | 5 |
|
| 3 | [coord] it [is] difficult [verb] whether | 5 |
|
