| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a long period [prep] | 162 |
|
| 2 | [conj] [prep] a period [prep] | 57 |
|
| 3 | [conj] [prep] a long period | 12 |
|
| 4 | [conj] a long period [prep] | 5 |
|
