| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficult [to-vb] [subord] [prep] | 44 |
|
| 2 | difficult [to-vb] because [prep] | 32 |
|
| 3 | difficult [to-vb] [subord] of | 29 |
|
| 4 | difficult [to-vb] [subord] of | 29 |
|
| 5 | difficult [to-vb] than [prep] | 5 |
|
