| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it have been [vb pp] on a | 15 |
|
| 2 | it has been [verb] on a | 10 |
|
| 3 | it 's been [verb] on a | 6 |
|
| 4 | it have been [v-ing] on a | 5 |
|
