| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could have [verb] [art] | 844 |
|
| 2 | could have [vb pp] [art] | 840 |
|
| 3 | [modal v] have produced [art] | 37 |
|
| 4 | could [verb] produced [art] | 5 |
|
| 5 | could have produce [art] | 5 |
|
