| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | and it is difficult [to-vb] [Wh adv] | 18 |
|
| 2 | and it is difficult [verb] how | 13 |
|
| 3 | and it is difficult see [Wh adv] | 12 |
|
| 4 | and it is difficult to see [Wh adv] | 12 |
|
