| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb -s] [vb pp] [prep] a time | 7 |
|
| 2 | [vb -s] [vb pp] at a time | 7 |
|
| 3 | [vb -s] [vb pp] at a time | 7 |
|
| 4 | has [vb pp] [prep] a time | 6 |
|
