| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] [been] working at the | 5 |
|
| 2 | [vb past] been working at the | 5 |
|
| 3 | [vb past] be working at the | 5 |
|
| 4 | had [be] working at the | 5 |
|
