| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | has been referred to | 51 |
|
| 2 | had been referred to | 24 |
|
| 3 | have been referred to | 19 |
|
| 4 | have been referred to | 6 |
|
| 5 | having been referred to | 5 |
|
