| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a specified period | 48 |
|
| 2 | [prep] a specified period | 48 |
|
| 3 | for a specified period | 22 |
|
| 4 | for a specified period | 22 |
|
| 5 | within a specified period | 17 |
|
| 6 | within a specified period | 17 |
|
