| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which could [not/n't] be | 160 |
|
| 2 | [Wh det] could not be | 157 |
|
| 3 | [Wh det] could n't be | 15 |
|
| 4 | what could [not/n't] be | 11 |
|
