| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be [verb] at a time | 5 |
|
| 2 | it be [vb pp] at a time | 5 |
|
| 3 | it be at a time when | 7 |
|
| 4 | it be at a time [adv] | 7 |
|
| 5 | it be at a time [Wh adv] | 7 |
|
| 6 | it be at a time when | 7 |
|
