| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could be [vb pp] [adv] | 1885 |
|
| 2 | could have be [vb pp] | 1042 |
|
| 3 | have be [vb pp] [adv] | 990 |
|
| 4 | could have [vb pp] [adv] | 628 |
|
| 5 | could have be [adv] | 249 |
|
