| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is difficult [to-vb] | 1523 |
|
| 2 | which it is difficult | 26 |
|
| 3 | which is difficult [to-vb] | 19 |
|
| 4 | which it is [to-vb] | 13 |
|
