| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [verb] [prep] [be] | 3823 |
|
| 2 | it [vb past] [prep] [be] | 1166 |
|
| 3 | [pron] happened [prep] [be] | 236 |
|
| 4 | it happen [prep] [be] | 77 |
|
