| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | there [be] a period | 59 |
|
| 2 | [ex0] be a period | 59 |
|
| 3 | [ex0] was a period | 44 |
|
| 4 | [ex0] [was/were] a period | 44 |
|
| 5 | [ex0] [is] a period | 14 |
|
| 6 | [ex0] is a period | 11 |
|
