| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be difficult [to-vb] [prep] | 114 |
|
| 2 | [be] difficult [to-vb] in | 38 |
|
| 3 | [be] difficult [to-vb] from | 13 |
|
| 4 | [be] difficult [to-vb] with | 12 |
|
| 5 | [be] difficult to distinguish [prep] | 12 |
|
| 6 | [be] difficult [to-vb] to | 10 |
|
| 7 | [be] difficult to obtain [prep] | 6 |
|
| 8 | [be] difficult [to-vb] at | 5 |
|
| 9 | [be] difficult [to-vb] on | 5 |
|
