| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have [been] difficult for | 21 |
|
| 2 | [vb infin] been difficult for | 21 |
|
| 3 | [vb infin] [been] difficult for | 21 |
|
| 4 | [vb infin] [been] difficult for | 21 |
|
