| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could have be | 2545 |
|
| 2 | could have been | 2541 |
|
| 3 | could have [been] | 2541 |
|
| 4 | could have [be] | 2482 |
|
| 5 | could 've [be] | 63 |
|
