| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pron] often happen | 46 |
|
| 2 | [pron] often happens | 40 |
|
| 3 | [pers pn] often happen | 38 |
|
| 4 | it often happen | 38 |
|
| 5 | it often happen | 38 |
|
| 6 | [Wh det] often happen | 8 |
|
| 7 | [pron] often happened | 6 |
|
| 8 | what often happen | 5 |
|
| 9 | what often happen | 5 |
|
