| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a period [prep] [adj] years | 244 |
|
| 2 | a period [prep] [adj] years | 244 |
|
| 3 | a period [prep] [adj] years | 244 |
|
| 4 | a period of [adj] years | 243 |
|
| 5 | a period of [adj] years | 243 |
|
| 6 | a period [prep] [num] years | 226 |
|
| 7 | a period [prep] two years | 34 |
|
| 8 | a period [prep] two years | 34 |
|
| 9 | a period [prep] five years | 31 |
|
| 10 | a period [prep] five years | 31 |
|
| 11 | a period [prep] three years | 29 |
|
| 12 | a period [prep] three years | 29 |
|
| 13 | a period [prep] [det] years | 17 |
|
| 14 | a period [prep] ten years | 12 |
|
| 15 | a period [prep] ten years | 12 |
|
| 16 | a period [prep] twenty years | 11 |
|
| 17 | a period [prep] twenty years | 11 |
|
| 18 | a period [prep] four years | 10 |
|
| 19 | a period [prep] four years | 10 |
|
| 20 | a period [prep] six years | 9 |
|
| 21 | a period [prep] six years | 9 |
|
| 22 | a period [prep] several years | 9 |
|
| 23 | a period [prep] several years | 9 |
|
| 24 | a period [prep] seven years | 7 |
|
| 25 | a period [prep] 10 years | 7 |
|
| 26 | a period [prep] seven years | 7 |
|
| 27 | a period [prep] 10 years | 7 |
|
| 28 | a period [prep] fifteen years | 5 |
|
| 29 | a period [prep] fifteen years | 5 |
|
| 30 | a period [prep] many years | 5 |
|
