| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adv] long period | 23 |
|
| 2 | for [art] [adv] long period | 11 |
|
| 3 | over [art] [adv] long period | 10 |
|
| 4 | [prep] [art] very long period | 8 |
|
