| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a [adv] long period of [noun sg] | 15 |
|
| 2 | a [adv] long period [prep] time | 13 |
|
| 3 | a [adv] long period [prep] [noun sg] | 12 |
|
| 4 | a very long period [prep] [noun sg] | 7 |
|
