| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a long period [prep] | 216 |
|
| 2 | [adv] a period [prep] | 117 |
|
| 3 | [adv] a long period | 41 |
|
| 4 | [adv] long period [prep] | 24 |
|
