| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] a period of [adj] [noun] | 15 |
|
| 2 | [adv] a period [prep] [adj] [noun sg] | 14 |
|
| 3 | [adv] a period [prep] [adj] [noun] | 13 |
|
