| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could have [verb] | 5175 |
|
| 2 | could have [vb pp] | 5143 |
|
| 3 | [modal v] have seen | 702 |
|
| 4 | could [verb] seen | 53 |
|
| 5 | could have seen | 53 |
|
| 6 | could [vb infin] seen | 53 |
|
| 7 | could have see | 52 |
|
