| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun] [prep] a prolonged period of | 10 |
|
| 2 | [noun] [prep] a prolonged period of | 10 |
|
| 3 | [noun] over a prolonged period of | 7 |
|
| 4 | [noun] over a prolonged period of | 7 |
|
| 5 | [noun sg] [prep] a prolonged period of | 7 |
|
