| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [Wh det] could have been [vb pp] | 75 |
|
| 2 | which could have been [vb pp] | 69 |
|
| 3 | [Wh det] could have been used | 9 |
|
| 4 | what could have been [vb pp] | 6 |
|
| 5 | [Wh det] could have been avoided | 5 |
|
