| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a long period [prep] | 85 |
|
| 2 | [verb] over a period [prep] | 76 |
|
| 3 | [verb] over a long period | 35 |
|
| 4 | [verb] a long period [prep] | 19 |
|
