| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [be] difficult [to-vb] at [adj] [noun] | 8 |
|
| 2 | be difficult [to-vb] at [adj] [noun] | 8 |
|
| 3 | [adv] difficult [to-vb] at [adj] [noun] | 6 |
|
| 4 | [adv] difficult [to-vb] at [adj] [noun] | 6 |
|
| 5 | difficult [to-vb] at [art] [adj] [noun] | 7 |
|
| 6 | difficult [to-vb] at [art] [adj] [noun] | 7 |
|
| 7 | difficult [to-vb] at a [adj] [noun] | 5 |
|
