| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | at [art] time when | 1607 |
|
| 2 | at [art] time when | 1596 |
|
| 3 | at a time when | 1342 |
|
| 4 | at the time when | 265 |
|
| 5 | at [art] times when | 11 |
|
