| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [subord] [prep] a [noun sg] | 2160 |
|
| 2 | once [prep] a [noun sg] | 396 |
|
| 3 | [subord] once a [noun sg] | 44 |
|
| 4 | [subord] once [prep] a | 10 |
|
