| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a period of | 1599 |
|
| 2 | [prep] a period of | 1599 |
|
| 3 | over a period of | 617 |
|
| 4 | over a period of | 617 |
|
| 5 | for a period of | 339 |
|
| 6 | for a period of | 339 |
|
| 7 | [verb] a period of | 297 |
|
| 8 | [be] a period of | 156 |
|
| 9 | be a period of | 156 |
|
| 10 | after a period of | 128 |
|
| 11 | after a period of | 128 |
|
| 12 | in a period of | 119 |
|
| 13 | in a period of | 119 |
|
| 14 | [adv] a period of | 110 |
|
| 15 | [conj] a period of | 82 |
|
| 16 | [was/were] a period of | 78 |
|
| 17 | during a period of | 72 |
|
| 18 | during a period of | 72 |
|
| 19 | [adv prt] a period of | 67 |
|
| 20 | [vb past] a period of | 67 |
|
| 21 | was a period of | 65 |
|
| 22 | over a period of | 61 |
|
| 23 | over a period of | 61 |
|
| 24 | [v-ing] a period of | 55 |
|
| 25 | [vb -s] a period of | 50 |
|
| 26 | within a period of | 47 |
|
| 27 | within a period of | 47 |
|
| 28 | through a period of | 46 |
|
| 29 | through a period of | 46 |
|
| 30 | of a period of | 44 |
|
