| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficult [to-vb] [conj] [noun] is | 9 |
|
| 2 | difficult [to-vb] [conj] [noun] [is] | 9 |
|
| 3 | difficult [to-vb] [subord] [noun] [is] | 6 |
|
