| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it has been [vb pp] [det] | 55 |
|
| 2 | it have been [vb pp] that | 51 |
|
| 3 | it have been [vb pp] several | 12 |
|
| 4 | it had been [vb pp] [det] | 12 |
|
| 5 | it 's been [vb pp] [det] | 12 |
|
| 6 | it have been suggested [det] | 10 |
|
| 7 | it have been shown [det] | 6 |
|
| 8 | it have been reported [det] | 5 |
|
| 9 | it have been [vb pp] many | 5 |
|
