| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is often [adj] [verb] | 214 |
|
| 2 | it is [adv] impossible [verb] | 179 |
|
| 3 | it is [adv] impossible [verb] | 174 |
|
| 4 | it [be] often impossible [verb] | 9 |
|
| 5 | it be often impossible [verb] | 9 |
|
| 6 | it is often impossible [verb] | 8 |
|
| 7 | it [is] often impossible [verb] | 8 |
|
| 8 | [pron] is often impossible [verb] | 8 |
|
