| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it has [adv] be [vb pp] before | 7 |
|
| 2 | it has [adv] [be] [vb pp] before | 7 |
|
| 3 | it has [adv] [been] [vb pp] before | 7 |
|
| 4 | it has [adv] been [vb pp] before | 7 |
|
