| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been a feature | 38 |
|
| 2 | has been a feature | 21 |
|
| 3 | [vb -s] been a feature | 21 |
|
| 4 | had been a feature | 11 |
|
| 5 | [vb past] been a feature | 11 |
|
