| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | at a time [prep] | 476 |
|
| 2 | [vb pp] at a time | 148 |
|
| 3 | [vb pp] a time [prep] | 11 |
|
| 4 | [vb pp] at time [prep] | 5 |
|
