| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which have occurred | 109 |
|
| 2 | which have occurred | 54 |
|
| 3 | which [vb base] occurred | 54 |
|
| 4 | which had occurred | 32 |
|
| 5 | which [vb past] occurred | 32 |
|
| 6 | which has occurred | 23 |
|
| 7 | which [vb -s] occurred | 23 |
|
