| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could [verb] [pron] | 12219 |
|
| 2 | could [vb infin] [pron] | 12148 |
|
| 3 | [modal v] have [pron] | 3510 |
|
| 4 | could have [pron] | 266 |
|
