| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | do [not/n't] know for certain | 11 |
|
| 2 | do not know for certain | 11 |
|
| 3 | do [adv] know for certain | 11 |
|
| 4 | do [adv] know for certain | 9 |
|
| 5 | do n't know for certain | 7 |
|
