| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | they could n't [vb infin] | 653 |
|
| 2 | [vb past] they could [vb infin] | 182 |
|
| 3 | [vb past] they could n't | 45 |
|
| 4 | [vb past] could n't [vb infin] | 6 |
|
