| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] twenty year | 403 |
|
| 2 | [v-ing] [prep] year | 140 |
|
| 3 | [v-ing] [prep] twenty | 63 |
|
| 4 | [v-ing] twenty year | 10 |
|
