| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which [vb mod] to | 138 |
|
| 2 | which [modal v] to | 138 |
|
| 3 | which used to | 71 |
|
| 4 | which used to | 71 |
|
| 5 | which ought to | 62 |
|
| 6 | which ought to | 62 |
|
