| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a period of time [conj] | 17 |
|
| 2 | over a period [prep] time [conj] | 17 |
|
| 3 | over a period [prep] time [coord] | 16 |
|
| 4 | over a period [prep] time and | 14 |
|
| 5 | over a period [prep] time and | 14 |
|
