| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] [prep] [prep] a | 140 |
|
| 2 | [prep] once [prep] a | 63 |
|
| 3 | [vb past] [prep] once [prep] | 60 |
|
| 4 | [vb past] once [prep] a | 13 |
|
