| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period [prep] [num] | 101 |
|
| 2 | during [art] [adj] period [prep] [num] | 16 |
|
| 3 | during a [adj] [noun] [prep] [num] | 15 |
|
| 4 | during a [adj] period [prep] [adj] | 8 |
|
