| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a [adj] period of years | 5 |
|
| 2 | over a [adj] period [prep] years | 5 |
|
| 3 | over a [adj] period [prep] years | 5 |
|
| 4 | over a [adj] period of years | 5 |
|
