| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | once [art] | 2973 |
|
| 2 | once a | 1996 |
|
| 3 | once a | 1878 |
|
| 4 | once the | 757 |
|
| 5 | once the | 757 |
|
| 6 | once every | 220 |
|
| 7 | once every | 220 |
|
| 8 | once an | 118 |
|
