| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | period [Wh adv] [noun sg] [noun] | 17 |
|
| 2 | period when [noun sg] [noun] | 16 |
|
| 3 | period when [noun sg] [noun] | 16 |
|
| 4 | period [adv] [noun sg] [noun sg] | 9 |
|
| 5 | period [adv] [noun sg] [noun pl] | 7 |
|
