| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | could be [v-ing] [prep] a [noun] | 12 |
|
| 2 | could [be] [v-ing] [prep] a [noun] | 12 |
|
| 3 | could [be] [v-ing] [prep] a [noun sg] | 10 |
|
