| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | of three years [unc] duration | 25 |
|
| 2 | [prep] three years ' duration | 25 |
|
| 3 | of three years [unc] duration | 25 |
|
| 4 | [prep] three years ['s] duration | 25 |
|
| 5 | [prep] three years ' duration | 25 |
|
| 6 | [prep] three years [unc] duration | 25 |
|
| 7 | [prep] three years [unc] duration | 25 |
|
