| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] be [prep] | 4611 |
|
| 2 | be operating [prep] | 299 |
|
| 3 | [vb past] be operating | 19 |
|
| 4 | [vb past] operating [prep] | 10 |
|
