| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] [adj] a period of | 10 |
|
| 2 | [prep] [adj] a period [prep] | 10 |
|
| 3 | [prep] [det] a period [prep] | 9 |
|
| 4 | [prep] such a period [prep] | 8 |
|
| 5 | [prep] such a period [prep] | 8 |
|
