| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [was/were] [v-ing] [prep] a time | 10 |
|
| 2 | was [v-ing] [prep] a time | 6 |
|
| 3 | [was/were] [v-ing] at a time | 6 |
|
| 4 | [was/were] [v-ing] at a time | 6 |
|
