| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is often [adj] | 322 |
|
| 2 | it is [adv] impossible | 302 |
|
| 3 | it is [adv] impossible | 255 |
|
| 4 | it [be] often impossible | 12 |
|
| 5 | it be often impossible | 12 |
|
| 6 | it is often impossible | 11 |
|
| 7 | it [is] often impossible | 11 |
|
| 8 | [pers pn] is often impossible | 11 |
|
| 9 | [pron] is often impossible | 11 |
|
| 10 | it is often impossible | 11 |
|
