| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [v-ing] [prep] four years | 19 |
|
| 2 | [v-ing] [prep] four years | 19 |
|
| 3 | [v-ing] for four years | 12 |
|
| 4 | [v-ing] for four years | 12 |
|
| 5 | [v-ing] four years [prep] | 6 |
|
| 6 | [v-ing] four years [prep] | 6 |
|
