| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [noun sg] [prep] a period | 40 |
|
| 2 | a [noun] [prep] a period | 31 |
|
| 3 | a [noun] for a period | 17 |
|
| 4 | a [noun] over a period | 12 |
|
| 5 | an [noun] [prep] a period | 9 |
|
