| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] [prep] [art] period of | 500 |
|
| 2 | [prep] [art] long period of | 150 |
|
| 3 | [verb] [prep] [art] long period | 74 |
|
| 4 | [verb] [art] long period of | 17 |
|
