| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | has occurred [prep] a [adj] | 21 |
|
| 2 | has occurred [prep] a previous | 18 |
|
| 3 | has occurred in a [adj] | 18 |
|
| 4 | has occurred [prep] a previous | 18 |
|
