| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adj] period of [noun] | 535 |
|
| 2 | [det] [adj] period of [noun] | 36 |
|
| 3 | [det] a [adj] period of | 10 |
|
| 4 | [det] a period of [noun] | 9 |
|
