| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | know [Wh adv] difficult it is [prep] | 6 |
|
| 2 | know how difficult it is [prep] | 6 |
|
| 3 | know [Wh adv] difficult it is [prep] | 6 |
|
| 4 | know [Wh adv] difficult it is for | 5 |
|
| 5 | know [Wh adv] difficult it is for | 5 |
|
