| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] difficult [to-vb] | 3607 |
|
| 2 | [not/n't] [adv] [to-vb] | 1750 |
|
| 3 | [not/n't] difficult [to-vb] | 274 |
|
| 4 | [not/n't] [adv] difficult | 164 |
|
