| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] over a period of | 60 |
|
| 2 | gradually over [art] period of | 7 |
|
| 3 | gradually over a period [prep] | 7 |
|
| 4 | gradually [prep] a period of | 7 |
|
| 5 | gradually over a period of | 7 |
|
| 6 | gradually over a [noun] of | 7 |
|
| 7 | gradually over a period [prep] | 7 |
|
| 8 | gradually over a period of | 7 |
|
| 9 | gradually over [art] period of | 7 |
|
| 10 | gradually over a period of | 7 |
|
| 11 | gradually [prep] a period of | 7 |
|
| 12 | gradually over a period of | 7 |
|
| 13 | gradually over a [noun sg] of | 7 |
|
