| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [modal v] be difficult for them | 7 |
|
| 2 | [vb mod] be difficult for them | 7 |
|
| 3 | be difficult for them [verb] | 9 |
|
| 4 | be difficult for them [to-vb] | 9 |
|
