| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it become [adj] [to-vb] | 229 |
|
| 2 | it [verb] difficult [to-vb] | 64 |
|
| 3 | [pers pn] become difficult [to-vb] | 27 |
|
| 4 | [pron] become difficult [to-vb] | 27 |
|
| 5 | it become difficult [verb] | 24 |
|
| 6 | it become difficult [to-vb] | 24 |
|
