| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could have heard a [noun] [verb] | 8 |
|
| 2 | could have heard [art] [noun] drop | 7 |
|
| 3 | could have heard [art] [noun] drop | 7 |
|
| 4 | could have hear a [noun] drop | 7 |
|
| 5 | could [vb infin] heard a [noun] drop | 7 |
|
| 6 | could have heard a [noun] drop | 7 |
|
| 7 | could [verb] heard a [noun] drop | 7 |
|
| 8 | [modal v] have heard a [noun] drop | 7 |
|
| 9 | could have heard a [noun] drop | 7 |
|
| 10 | could have [verb] a [noun] drop | 7 |
|
| 11 | could have [vb pp] a [noun] drop | 7 |
|
