| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] [adv] a year | 355 |
|
| 2 | [v-ing] [prep] [adv] a | 162 |
|
| 3 | [v-ing] [prep] a year | 49 |
|
| 4 | [v-ing] [adv] a year | 18 |
|
