| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | not [verb] for certain | 15 |
|
| 2 | not know for certain | 12 |
|
| 3 | not [vb infin] for certain | 8 |
|
| 4 | not known for certain | 7 |
|
| 5 | not [vb pp] for certain | 7 |
|
| 6 | not know for certain | 5 |
|
