| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | back [prep] [art] period [prep] | 8 |
|
| 2 | back [prep] [art] period [prep] | 8 |
|
| 3 | back [prep] [art] period [prep] | 8 |
|
| 4 | back [prep] [art] period of | 5 |
|
| 5 | back [prep] [art] period of | 5 |
|
| 6 | back [prep] a period [prep] | 5 |
|
