| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which [vb base] [pron] difficult [verb] | 5 |
|
| 2 | [Wh det] [vb base] [pron] difficult [verb] | 5 |
|
| 3 | [Wh det] [vb base] [pers pn] difficult [verb] | 5 |
|
| 4 | [Wh det] [vb base] [pron] difficult [to-vb] | 5 |
|
