| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be difficult [prep] us [verb] | 15 |
|
| 2 | it be difficult for us [verb] | 15 |
|
| 3 | it be difficult for us [verb] | 15 |
|
| 4 | it be difficult [prep] us [verb] | 15 |
|
| 5 | it be difficult [prep] us [to-vb] | 15 |
|
| 6 | it be difficult [prep] us [verb] | 15 |
|
| 7 | it is difficult [prep] us [verb] | 12 |
|
