| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is difficult [to-vb] such a [noun] | 5 |
|
| 2 | is difficult [verb] such a [noun] | 5 |
|
| 3 | is difficult [verb] such a [noun] | 5 |
|
| 4 | is difficult [verb] such a [noun sg] | 5 |
|
