| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | at [noun prp] [prep] a [noun] | 221 |
|
| 2 | at [noun prp] [prep] a [noun sg] | 202 |
|
| 3 | [prep] [noun prp] [prep] a while | 45 |
|
| 4 | at [noun] [prep] a while | 17 |
|
| 5 | at [noun prp] [prep] a while | 5 |
|
| 6 | at [noun prp] [prep] [art] while | 5 |
|
