| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [modal v] [vb infin] or [vb infin] | 808 |
|
| 2 | could [vb infin] [conj] [vb infin] | 617 |
|
| 3 | could [vb infin] or [verb] | 111 |
|
| 4 | could [verb] or [vb infin] | 111 |
|
