| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [num] years ' duration | 70 |
|
| 2 | [num] year ' duration | 70 |
|
| 3 | four year ' duration | 27 |
|
| 4 | three year ' duration | 25 |
|
| 5 | two year ' duration | 7 |
|
