| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | had been [vb pp] for years | 10 |
|
| 2 | have been [vb pp] for years | 10 |
|
| 3 | have been used for years | 6 |
|
| 4 | has been [vb pp] for years | 5 |
|
