| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period | 2001 |
|
| 2 | a [adj] period in | 130 |
|
| 3 | [prep] a [adj] in | 111 |
|
| 4 | [prep] [adj] period in | 102 |
|
| 5 | [prep] a period in | 72 |
|
