| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [vb pp] [prep] a | 8810 |
|
| 2 | [vb pp] [prep] a period | 269 |
|
| 3 | is [prep] a period | 9 |
|
| 4 | is [vb pp] [prep] period | 8 |
|
