| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] at a time | 345 |
|
| 2 | occur at a [noun] | 59 |
|
| 3 | occur at a [noun sg] | 58 |
|
| 4 | occur at [art] time | 31 |
|
| 5 | occur [prep] a time | 20 |
|
| 6 | occur at a time | 18 |
|
