| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficult [to-vb] [conj] [art] | 200 |
|
| 2 | [not/n't] [to-vb] [conj] [art] | 164 |
|
| 3 | [not/n't] difficult [to-vb] [art] | 48 |
|
| 4 | [not/n't] difficult [to-vb] [conj] | 36 |
|
