| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [Wh pn] happened [prep] be [verb] [prep] | 7 |
|
| 2 | [Wh pn] happened [prep] be [v-ing] [prep] | 6 |
|
| 3 | [Wh pn] happened [prep] be [prep] [art] | 7 |
|
| 4 | [Wh pn] happened [prep] be [prep] [art] | 7 |
|
| 5 | [Wh pn] happened [prep] be [prep] the | 6 |
|
| 6 | [Wh pn] happened [prep] be [prep] the | 6 |
|
