| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb mod] have been a [adj] idea | 8 |
|
| 2 | [modal v] have been a [adj] idea | 8 |
|
| 3 | might have been a [adj] idea | 5 |
|
| 4 | might have been a [adj] idea | 5 |
|
