| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [coord] [noun] [prep] a period of | 18 |
|
| 2 | [coord] [noun] [prep] a period of | 18 |
|
| 3 | and [noun] [prep] a period of | 12 |
|
| 4 | [coord] [noun] over a period of | 9 |
|
| 5 | [coord] [noun sg] [prep] a period of | 9 |
|
| 6 | or [noun] [prep] a period of | 6 |
|
| 7 | [coord] [noun pl] [prep] a period of | 5 |
|
