| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could have heard a [noun] drop | 7 |
|
| 2 | could have hear a [noun] drop | 7 |
|
| 3 | could have hear a pin drop | 7 |
|
| 4 | could have hear a [noun sg] drop | 7 |
|
| 5 | could have hear a pin drop | 7 |
|
