| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] once [been] an [noun] | 5 |
|
| 2 | have once [been] an [noun] | 5 |
|
| 3 | had once [been] an [noun] | 5 |
|
| 4 | [verb] once [been] an [noun] | 5 |
|
