| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period [prep] | 773 |
|
| 2 | [prep] a fixed [noun sg] [prep] | 189 |
|
| 3 | [prep] a fixed [noun] [prep] | 189 |
|
| 4 | [prep] [art] fixed period [prep] | 30 |
|
| 5 | [prep] [art] fixed period [prep] | 30 |
|
| 6 | [prep] a fixed period [prep] | 29 |
|
| 7 | [prep] a fixed period [prep] | 29 |
|
