| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | as it is difficult [verb] | 18 |
|
| 2 | as it [is] difficult [verb] | 18 |
|
| 3 | as it [is] difficult [to-vb] | 18 |
|
| 4 | as it [is] difficult [verb] | 18 |
|
