| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a long period [prep] | 162 |
|
| 2 | [prep] a [adv] long period | 23 |
|
| 3 | [prep] [adv] long period [prep] | 14 |
|
| 4 | a [adv] long period [prep] | 14 |
|
