| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [Wh adv] [pron] could [verb] | 765 |
|
| 2 | [Wh adv] [pron] could [vb infin] | 763 |
|
| 3 | [Wh adv] [pron] [modal v] have | 556 |
|
| 4 | [adv] [pron] could have | 482 |
|
| 5 | [Wh adv] [pron] could have | 113 |
|
