| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it could [vb infin] | 2635 |
|
| 2 | [vb past] it [vb infin] | 1350 |
|
| 3 | [vb past] it could | 231 |
|
| 4 | [vb past] could [vb infin] | 53 |
|
