| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [noun] [prep] | 149102 |
|
| 2 | [prep] [art] period [prep] | 3161 |
|
| 3 | [prep] [art] period [prep] | 3161 |
|
| 4 | [prep] a period [prep] | 1754 |
|
| 5 | [prep] a period [prep] | 1753 |
|
