| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | once a [noun] | 1633 |
|
| 2 | once a [noun sg] | 1606 |
|
| 3 | [adv] a quarter | 670 |
|
| 4 | [adv] a quarter | 645 |
|
| 5 | once a quarter | 9 |
|
| 6 | once [art] quarter | 9 |
|
| 7 | once a quarter | 9 |
|
