| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [v-ing] [prep] a time when | 30 |
|
| 2 | [v-ing] [prep] a time when | 30 |
|
| 3 | [v-ing] at a time when | 25 |
|
| 4 | [v-ing] at a time when | 25 |
|
