| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a period in | 72 |
|
| 2 | for a period in | 19 |
|
| 3 | for a period in | 19 |
|
| 4 | after a period in | 15 |
|
| 5 | after a period in | 15 |
|
| 6 | during a period in | 8 |
|
| 7 | during a period in | 8 |
|
| 8 | in a period in | 5 |
|
| 9 | in a period in | 5 |
|
