| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a prolonged period of | 8 |
|
| 2 | over a prolonged [noun] of | 8 |
|
| 3 | over a prolonged [noun] of | 8 |
|
| 4 | over a prolonged [noun] of | 8 |
|
| 5 | over a prolonged [noun sg] of | 8 |
|
| 6 | over a prolonged period of | 8 |
|
