| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [vb pp] [prep] a [adj] period | 70 |
|
| 2 | be [vb pp] [prep] a long [noun] | 53 |
|
| 3 | be [vb pp] [prep] a long period | 34 |
|
| 4 | [be] [vb pp] [prep] a long period | 34 |
|
| 5 | be [vb pp] [prep] [art] long period | 15 |
|
| 6 | be [vb pp] [prep] [art] long period | 15 |
|
| 7 | be [vb pp] [prep] a long period | 14 |
|
| 8 | be [verb] [prep] a long period | 14 |
|
| 9 | be [vb pp] [prep] a long period | 14 |
|
| 10 | [be] [vb pp] [prep] a long period | 14 |
|
