| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [Wh adv] did it happen | 57 |
|
| 2 | [Wh adv] [vb past] it happen | 57 |
|
| 3 | how [vb past] it happen | 34 |
|
| 4 | when [vb past] it happen | 11 |
|
| 5 | why [vb past] it happen | 9 |
|
