| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] what have happened to | 142 |
|
| 2 | know what have happened to | 50 |
|
| 3 | [vb infin] what have happened to | 39 |
|
| 4 | know what have happened [prep] | 27 |
|
| 5 | know what have [verb] to | 24 |
|
| 6 | know what have [vb pp] to | 24 |
|
| 7 | know [pron] have happened to | 24 |
|
| 8 | know what [verb] happened to | 24 |
|
| 9 | know what have happen to | 24 |
|
