| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun sg] [Wh det] [modal v] be difficult | 11 |
|
| 2 | [noun sg] [Wh det] [modal v] [be] difficult | 11 |
|
| 3 | [noun sg] which [modal v] [be] difficult | 11 |
|
| 4 | [noun sg] [Wh det] [vb mod] [be] difficult | 11 |
|
