| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it have been [vb pp] for a | 18 |
|
| 2 | it 's been [verb] for a | 11 |
|
| 3 | it has been [verb] for a | 10 |
|
| 4 | it have been [v-ing] for a | 8 |
|
| 5 | it have been know for a | 6 |
|
| 6 | it have been known for a | 6 |
|
| 7 | it had been [verb] for a | 5 |
|
