| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] over a period | 65 |
|
| 2 | [vb past] over a period | 21 |
|
| 3 | [v-ing] over a period | 13 |
|
| 4 | [vb -s] over a period | 8 |
|
| 5 | [vb infin] over a period | 7 |
|
| 6 | [vb base] over a period | 7 |
|
| 7 | [to-vb] over a period | 6 |
|
| 8 | occur over a period | 6 |
|
| 9 | extend over a period | 5 |
|
| 10 | over a [adj] period | 72 |
|
| 11 | over a [adj] period | 70 |
|
| 12 | over a long period | 34 |
|
| 13 | over a long period | 32 |
|
| 14 | over a period [prep] | 62 |
|
| 15 | over a period [prep] | 62 |
|
| 16 | over a period of | 61 |
|
| 17 | over a period of | 61 |
|
