| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] how difficult it is [prep] | 15 |
|
| 2 | [vb base] how difficult it is [prep] | 8 |
|
| 3 | know how difficult it is [prep] | 6 |
|
| 4 | know how difficult it is [prep] | 6 |
|
| 5 | how difficult it is [verb] [prep] | 9 |
|
| 6 | how difficult it is [to-vb] [prep] | 5 |
|
| 7 | how difficult it is [prep] [noun] | 10 |
|
| 8 | how difficult it is [prep] [noun pl] | 6 |
|
