| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could have [verb] [adv prt] | 274 |
|
| 2 | could have [verb] a | 273 |
|
| 3 | could [verb] [adv prt] a | 162 |
|
| 4 | have [verb] [adv prt] a | 117 |
|
