| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] [prep] a long | 513 |
|
| 2 | [prep] a long period | 391 |
|
| 3 | [adv] [prep] a period | 178 |
|
| 4 | [adv] a long period | 43 |
|
