| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun sg] [prep] a [adj] period | 519 |
|
| 2 | [noun sg] [prep] a certain [noun] | 433 |
|
| 3 | [noun sg] [prep] a certain [noun sg] | 418 |
|
| 4 | [noun] [prep] a certain period | 14 |
|
| 5 | [noun sg] [prep] a certain period | 12 |
|
| 6 | [noun sg] [prep] [art] certain period | 12 |
|
| 7 | [noun sg] [prep] a certain period | 12 |
|
| 8 | [noun sg] [prep] [art] certain period | 12 |
|
| 9 | [noun sg] [prep] a certain period | 12 |
|
