| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [modal v] have [been] [adv] [prep] | 157 |
|
| 2 | could have [been] [adv] [prep] | 20 |
|
| 3 | could [verb] [been] [adv] [prep] | 15 |
|
| 4 | could have [be] [adv] [prep] | 15 |
|
