| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a period of [noun] | 296 |
|
| 2 | over a period of [adj] | 224 |
|
| 3 | over a period of [num] | 191 |
|
| 4 | over a period of [noun sg] | 186 |
|
| 5 | over a period of time | 184 |
|
| 6 | over a period of time | 184 |
|
| 7 | over a period of [noun pl] | 110 |
|
| 8 | over a period of years | 62 |
|
| 9 | over a period of year | 62 |
|
| 10 | over a period of [adv] | 40 |
|
| 11 | over a period of [adv] | 37 |
|
| 12 | over a period of two | 33 |
|
| 13 | over a period of two | 33 |
|
| 14 | over a period of [det] | 32 |
|
| 15 | over a period of a | 27 |
|
| 16 | over a period of three | 27 |
|
| 17 | over a period of a | 27 |
|
| 18 | over a period of [art] | 27 |
|
| 19 | over a period of [art] | 27 |
|
| 20 | over a period of three | 27 |
|
| 21 | over a period of week | 19 |
|
| 22 | over a period of weeks | 19 |
|
| 23 | over a period of month | 17 |
|
| 24 | over a period of months | 17 |
|
| 25 | over a period of several | 16 |
|
| 26 | over a period of several | 16 |
|
| 27 | over a period of [prep] | 16 |
|
| 28 | over a period of [prep] | 16 |
|
| 29 | over a period of five | 14 |
|
| 30 | over a period of about | 14 |
|
