| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is difficult [not/n't] [to-vb] [that] | 7 |
|
| 2 | is difficult [not/n't] [verb] [that] | 7 |
|
| 3 | is difficult not [verb] [that] | 7 |
|
| 4 | is difficult [not/n't] [verb] that | 7 |
|
