| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficult [to-vb] [pron] [noun sg] | 149 |
|
| 2 | [adj] [to-vb] which [noun sg] | 51 |
|
| 3 | difficult [to-vb] which [noun] | 29 |
|
| 4 | difficult [verb] which [noun sg] | 15 |
|
