| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb mod] [adv] happen | 703 |
|
| 2 | [vb mod] happen to | 507 |
|
| 3 | [adv] happen to | 484 |
|
| 4 | [vb mod] [adv] to | 245 |
|
