| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | not possible [verb] a | 58 |
|
| 2 | not [been] possible [verb] | 41 |
|
| 3 | not [been] [verb] a | 32 |
|
| 4 | [been] possible [verb] a | 16 |
|
