| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adj] period [prep] [noun sg] | 670 |
|
| 2 | over a period [prep] [noun sg] | 187 |
|
| 3 | over a [adj] period [prep] | 183 |
|
| 4 | over [adj] period [prep] [noun sg] | 7 |
|
