| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | occur at a | 95 |
|
| 2 | occurred at a | 33 |
|
| 3 | occurs at a | 26 |
|
| 4 | occurring at a | 23 |
|
| 5 | occur at an | 22 |
|
| 6 | occurred at a | 11 |
|
| 7 | occur at a | 10 |
|
| 8 | occur at a | 8 |
|
| 9 | to occur at a | 6 |
|
