| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj] period | 1796 |
|
| 2 | [prep] a long period | 391 |
|
| 3 | [prep] a longer [noun] | 228 |
|
| 4 | [prep] a longer [noun sg] | 227 |
|
| 5 | [prep] a [adj -er] period | 146 |
|
| 6 | [prep] [art] longer period | 89 |
|
| 7 | [prep] [art] longer period | 89 |
|
| 8 | [prep] a longer period | 86 |
|
| 9 | [prep] a longer period | 86 |
|
