| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] once [prep] a | 63 |
|
| 2 | [prep] once [prep] a | 55 |
|
| 3 | at once [prep] a | 50 |
|
| 4 | at once [prep] a | 50 |
|
| 5 | [prep] once in a | 14 |
|
| 6 | [prep] once with a | 8 |
|
| 7 | [prep] once [prep] an | 8 |
|
| 8 | [prep] once by a | 8 |
|
| 9 | [prep] once to a | 7 |
|
| 10 | [prep] once into a | 6 |
|
| 11 | for once [prep] a | 6 |
|
| 12 | for once [prep] a | 6 |
|
