| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun] [modal v] [verb] [prep] a time | 13 |
|
| 2 | [noun] [vb mod] [verb] [prep] a time | 13 |
|
| 3 | [noun] [modal v] [vb infin] [prep] a time | 12 |
|
| 4 | [noun sg] [modal v] [verb] [prep] a time | 10 |
|
| 5 | [noun] [modal v] [verb] at a time | 6 |
|
| 6 | [noun] [modal v] [verb] at a time | 6 |
|
