| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be impossible [prep] be [adj] | 30 |
|
| 2 | it be impossible to be [adj] | 30 |
|
| 3 | it is impossible [prep] be [adj] | 19 |
|
| 4 | it be impossible [prep] be sure | 9 |
|
| 5 | it was impossible [prep] be [adj] | 7 |
|
| 6 | it be impossible [prep] be certain | 7 |
|
