| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be difficult because it [be] | 5 |
|
| 2 | [be] difficult because it [be] | 5 |
|
| 3 | difficult [verb] because it [be] | 5 |
|
| 4 | difficult [to-vb] because it [be] | 5 |
|
