| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [be] difficult [prep] [indef pn] | 23 |
|
| 2 | [be] [prep] [indef pn] [to-vb] | 19 |
|
| 3 | difficult [prep] [indef pn] [to-vb] | 17 |
|
