| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] a long period [prep] | 26 |
|
| 2 | [verb] a long period [prep] | 19 |
|
| 3 | [verb] a long period of | 16 |
|
| 4 | [verb] a long period of | 16 |
|
| 5 | [vb pp] a long period [prep] | 9 |
|
| 6 | [verb] a longer period [prep] | 7 |
|
| 7 | [vb past] a long period [prep] | 6 |
|
| 8 | have a long period [prep] | 5 |
|
