| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | what have happen | 1985 |
|
| 2 | what [verb] happened | 1979 |
|
| 3 | what [vb -s] happen | 1053 |
|
| 4 | what [vb past] happen | 1007 |
|
| 5 | what had happen | 975 |
|
| 6 | what 's happen | 530 |
|
| 7 | what has happen | 478 |
|
| 8 | what [verb] to happen | 44 |
|
| 9 | what [verb] happen | 35 |
|
| 10 | what do happen | 35 |
|
| 11 | what did happen | 27 |
|
| 12 | what tends happen | 24 |
|
| 13 | what tend happen | 24 |
|
| 14 | what does happen | 8 |
|
| 15 | what needs happen | 5 |
|
| 16 | what need happen | 5 |
|
