| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | for a long period [prep] | 33 |
|
| 2 | for a long period [prep] | 27 |
|
| 3 | for a long period of | 21 |
|
| 4 | for a long period of | 21 |
|
| 5 | for a longer period [prep] | 6 |
|
