| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period | 1796 |
|
| 2 | [prep] a [adj] for | 103 |
|
| 3 | a [adj] period for | 42 |
|
| 4 | [prep] [adj] period for | 11 |
|
