| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | that did [adv] happen | 9 |
|
| 2 | that [vb past] not happen | 9 |
|
| 3 | that [vb past] [not/n't] happen | 9 |
|
| 4 | that [vb past] n't happen | 6 |
|
