| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] [prep] a [noun sg] of time | 17 |
|
| 2 | [adv] [prep] a period of time | 15 |
|
| 3 | [adv] [prep] a period of time | 15 |
|
| 4 | [adv] over a [noun] of time | 10 |
|
