| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [prep] [adv] a | 270 |
|
| 2 | be [prep] once [art] | 46 |
|
| 3 | be [prep] once [art] | 46 |
|
| 4 | be [prep] once a | 29 |
|
| 5 | [be] [prep] once a | 22 |
|
