| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | occur at a [noun sg] | 53 |
|
| 2 | occurred at a [noun sg] | 19 |
|
| 3 | occur at a time | 18 |
|
| 4 | occurs at a [noun sg] | 13 |
|
| 5 | occurring at a [noun sg] | 11 |
|
| 6 | occur at a rate | 7 |
|
| 7 | occurred at a [noun sg] | 6 |
|
| 8 | occur at an [noun sg] | 5 |
|
