| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could [adv] have [vb pp] [prep] | 163 |
|
| 2 | [adv] have [vb pp] [prep] a | 152 |
|
| 3 | could have [vb pp] [prep] a | 78 |
|
| 4 | could [adv] have [vb pp] a | 48 |
|
