| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficult [to-vb] [adv] how | 24 |
|
| 2 | difficult [to-vb] [adv] how | 23 |
|
| 3 | difficult [to-vb] just how | 11 |
|
| 4 | difficult [to-vb] just how | 11 |
|
| 5 | difficult [to-vb] exactly how | 8 |
|
| 6 | difficult [to-vb] exactly how | 8 |
|
