| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv prt] a [adj] period [prep] | 23 |
|
| 2 | [adv prt] a [adj] period [prep] | 23 |
|
| 3 | [adv prt] a [adj] period of | 19 |
|
| 4 | [adv prt] a [adj] period of | 19 |
|
| 5 | over a [adj] period [prep] | 19 |
|
| 6 | [adv prt] a long period [prep] | 9 |
|
| 7 | [adv prt] a long period [prep] | 9 |
|
