| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [v-ing] [prep] [verb] when | 32 |
|
| 2 | [v-ing] [prep] [vb infin] when | 28 |
|
| 3 | [v-ing] [prep] happen [conj] | 17 |
|
| 4 | [v-ing] [prep] happen when | 7 |
|
| 5 | [verb] [prep] happen when | 7 |
|
