| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adv] [adj] period of | 94 |
|
| 2 | a [adv] long [noun] of | 50 |
|
| 3 | [art] [adv] long period of | 24 |
|
| 4 | a [adv] long period [prep] | 20 |
|
| 5 | a [adv] long period [prep] | 20 |
|
| 6 | a [adv] long period of | 18 |
|
