| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could [verb] been used [prep] [noun] | 7 |
|
| 2 | could [vb infin] been used [prep] [noun] | 7 |
|
| 3 | could have been used [prep] [noun] | 7 |
|
| 4 | could [verb] been used [prep] [noun] | 7 |
|
| 5 | could have been used [prep] [noun] | 7 |
|
| 6 | could [verb] been used [prep] [noun sg] | 5 |
|
