| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [prep] a [noun] | 9866 |
|
| 2 | be once a [noun] | 141 |
|
| 3 | [prep] once a [noun] | 64 |
|
| 4 | be [prep] once a | 29 |
|
| 5 | be [prep] once [noun] | 5 |
|
