| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it has been [vb pp] for [noun pl] | 12 |
|
| 2 | it had been [vb pp] for [noun pl] | 9 |
|
| 3 | it have been known for [noun pl] | 8 |
|
| 4 | it have been [vb pp] for centuries | 6 |
|
