| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a period of [adj] years | 212 |
|
| 2 | [prep] a period of [adj] years | 212 |
|
| 3 | over a period of [adj] [noun] | 190 |
|
| 4 | over a period of [adj] [noun pl] | 186 |
|
| 5 | over a [noun sg] of [adj] years | 113 |
|
| 6 | over a [noun] of [adj] years | 113 |
|
| 7 | over a period of [adj] year | 112 |
|
| 8 | over [art] period of [adj] years | 110 |
|
| 9 | over [art] period of [adj] years | 110 |
|
| 10 | over a period of [adj] years | 109 |
|
| 11 | over a period [prep] [adj] years | 109 |
|
| 12 | over a period of [adj] years | 109 |
|
| 13 | over a period of [adj] years | 109 |
|
