| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a period | 2137 |
|
| 2 | over a period | 681 |
|
| 3 | for a period | 517 |
|
| 4 | in a period | 180 |
|
| 5 | after a period | 175 |
|
| 6 | during a period | 110 |
|
| 7 | of a period | 74 |
|
| 8 | to a period | 63 |
|
| 9 | through a period | 55 |
|
| 10 | with a period | 54 |
|
| 11 | within a period | 50 |
|
| 12 | as a period | 41 |
|
| 13 | by a period | 37 |
|
| 14 | from a period | 27 |
|
| 15 | at a period | 17 |
|
| 16 | on a period | 13 |
|
| 17 | into a period | 11 |
|
| 18 | before a period | 6 |
|
| 19 | about a period | 6 |
|
