| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is difficult [verb] | 1529 |
|
| 2 | it is difficult [to-vb] | 1523 |
|
| 3 | it is [adj] to distinguish | 138 |
|
| 4 | it be difficult to distinguish | 22 |
|
| 5 | it [be] difficult to distinguish | 22 |
|
| 6 | [pron] is difficult to distinguish | 21 |
|
| 7 | it is difficult to distinguish | 20 |
|
| 8 | [pers pn] is difficult to distinguish | 20 |
|
| 9 | it is difficult distinguish | 20 |
|
| 10 | it [is] difficult to distinguish | 20 |
|
