| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb mod] [verb] is | 1936 |
|
| 2 | [vb mod] happen [be] | 64 |
|
| 3 | [vb mod] happen be | 64 |
|
| 4 | [modal v] happen is | 53 |
|
| 5 | [vb mod] happen [is] | 53 |
|
