| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [adj -er] period than | 18 |
|
| 2 | [prep] a [adj -er] period than | 18 |
|
| 3 | for a [adj -er] period than | 12 |
|
| 4 | [prep] a longer period than | 12 |
|
| 5 | for a [adj -er] period than | 12 |
|
