| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could n't [vb infin] [adv] | 1419 |
|
| 2 | [modal v] n't [vb infin] back | 232 |
|
| 3 | could [adv] [vb infin] back | 130 |
|
| 4 | could not [vb infin] back | 68 |
|
| 5 | could [not/n't] [vb infin] back | 68 |
|
| 6 | could n't [verb] back | 50 |
|
