| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [not/n't] know for certain | 20 |
|
| 2 | [not/n't] know for certain | 13 |
|
| 3 | not know for certain | 12 |
|
| 4 | n't know for certain | 8 |
|
| 5 | [not/n't] known for certain | 7 |
|
