| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a long period [prep] | 93 |
|
| 2 | [verb] over a period [prep] | 76 |
|
| 3 | [verb] over a long period | 46 |
|
| 4 | [verb] a long period [prep] | 26 |
|
