| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | know how [adj] it is [prep] | 17 |
|
| 2 | [verb] how difficult it is [prep] | 15 |
|
| 3 | know [adv] difficult it is [prep] | 6 |
|
| 4 | know how difficult [pers pn] is [prep] | 6 |
|
| 5 | know how difficult [pron] is [prep] | 6 |
|
| 6 | know how difficult it be [prep] | 6 |
|
| 7 | know how difficult it [is] [prep] | 6 |
|
| 8 | know how difficult it is [prep] | 6 |
|
| 9 | know how difficult it [be] [prep] | 6 |
|
