| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] [been] [prep] | 4108 |
|
| 2 | [been] operating [prep] | 60 |
|
| 3 | [vb past] [been] operating | 19 |
|
| 4 | [vb past] operating [prep] | 10 |
|
