| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a certain [noun] | 2027 |
|
| 2 | [prep] a certain [noun sg] | 1991 |
|
| 3 | [prep] a [adj] period | 1796 |
|
| 4 | [prep] a certain period | 42 |
|
| 5 | [prep] [art] certain period | 42 |
|
| 6 | [prep] a certain period | 42 |
|
| 7 | [prep] [art] certain period | 42 |
|
| 8 | [prep] a certain period | 42 |
|
