| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] [det] a long period | 10 |
|
| 2 | [prep] [det] a long period | 10 |
|
| 3 | [prep] such a long period | 10 |
|
| 4 | over [det] a long period | 5 |
|
| 5 | over [det] a long period | 5 |
|
