| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adj] [to-vb] at | 1553 |
|
| 2 | difficult [to-vb] [prep] | 1432 |
|
| 3 | difficult [to-vb] [prep] | 1432 |
|
| 4 | difficult [verb] at | 76 |
|
| 5 | difficult [to-vb] at | 75 |
|
