| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [subord] [prep] a [noun] | 2247 |
|
| 2 | once [prep] a [noun] | 401 |
|
| 3 | [subord] once a [noun] | 46 |
|
| 4 | [subord] once [prep] [noun] | 11 |
|
| 5 | [subord] once [prep] a | 10 |
|
