| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] [prep] a long period | 67 |
|
| 2 | [was/were] [vb pp] [prep] a long | 51 |
|
| 3 | [was/were] [vb pp] [prep] a period | 42 |
|
| 4 | [was/were] [vb pp] [prep] long period | 10 |
|
