| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] once [conj] [adv] a [noun] | 17 |
|
| 2 | [adv] once [conj] [adv] a [noun sg] | 17 |
|
| 3 | [adv] once [conj] [adv] a year | 6 |
|
| 4 | [adv] once [conj] [adv] a year | 6 |
|
