| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [num] week period | 18 |
|
| 2 | [prep] a [num] week period | 18 |
|
| 3 | over a [num] week period | 13 |
|
| 4 | [prep] a two week period | 6 |
|
