| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [was/were] [vb pp] at a time when | 29 |
|
| 2 | [was/were] [vb pp] at a time [Wh adv] | 29 |
|
| 3 | was [vb pp] at a time [Wh adv] | 21 |
|
| 4 | were [vb pp] at a time [Wh adv] | 8 |
|
