| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] over a period of [noun] | 39 |
|
| 2 | [adv] over a period [prep] time | 22 |
|
| 3 | [adv] over a period [prep] [noun sg] | 22 |
|
| 4 | [adv] over a period [prep] time | 22 |
|
| 5 | [adv prt] over a period [prep] [noun] | 20 |
|
| 6 | [adv] over a period [prep] [noun] | 18 |
|
| 7 | [adv] over a period [prep] [noun pl] | 17 |
|
| 8 | [adv] over a period [prep] year | 7 |
|
| 9 | up over a period [prep] [noun] | 7 |
|
| 10 | [adv] over a period [prep] years | 7 |
|
| 11 | up over a period [prep] [noun] | 7 |
|
| 12 | [adv] over a period [prep] week | 5 |
|
| 13 | [adv] over a period [prep] weeks | 5 |
|
