| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [was/were] [prep] [det] period | 40 |
|
| 2 | was [prep] [det] period | 37 |
|
| 3 | [was/were] [prep] this period | 36 |
|
| 4 | [was/were] during [det] period | 20 |
|
| 5 | [was/were] during [det] period | 20 |
|
| 6 | [was/were] in [det] period | 10 |
|
| 7 | [was/were] in [det] period | 10 |
|
| 8 | [was/were] at [det] period | 5 |
|
| 9 | [was/were] at [det] period | 5 |
|
