| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [be] [prep] four years ' duration | 18 |
|
| 2 | be [prep] four years ' duration | 18 |
|
| 3 | [be] [prep] four years ' duration | 18 |
|
| 4 | [be] [prep] four years ' duration | 18 |
|
| 5 | [be] of four years ' duration | 17 |
|
| 6 | [is] [prep] four years ' duration | 15 |
|
| 7 | is [prep] four years ' duration | 15 |
|
