| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [num] year [adv] at a [noun] | 12 |
|
| 2 | [num] [noun] [adv] at a time | 11 |
|
| 3 | [num] year [adv] at a [noun sg] | 11 |
|
| 4 | [num] year [adv] at [art] time | 9 |
|
| 5 | [num] year [adv] at a time | 5 |
|
| 6 | [num] year [adv] [prep] a time | 5 |
|
| 7 | [num] year [adv] at a time | 5 |
|
| 8 | [adj] year [adv] at a time | 5 |
|
| 9 | [num] year [adv] [prep] a time | 5 |
|
