| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [prep] [adj] years ' duration | 45 |
|
| 2 | is [prep] [adj] years ' duration | 45 |
|
| 3 | is [prep] [num] years ' duration | 45 |
|
| 4 | is of [adj] years ' duration | 44 |
|
| 5 | is [prep] three years ' duration | 24 |
|
| 6 | is [prep] three years ' duration | 24 |
|
| 7 | is [prep] four years ' duration | 15 |
|
| 8 | is [prep] four years ' duration | 15 |
|
| 9 | is [prep] two years ' duration | 6 |
|
| 10 | is [prep] two years ' duration | 6 |
|
