| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is [adv] difficult [to-vb] | 554 |
|
| 2 | it is difficult [to-vb] [adj] | 193 |
|
| 3 | is [adv] difficult [to-vb] [adj] | 82 |
|
| 4 | it [adv] difficult [to-vb] [adj] | 43 |
|
| 5 | it is [adv] [to-vb] [adj] | 11 |
|
