| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] been [verb] | 40184 |
|
| 2 | [vb past] been [v-ing] | 6932 |
|
| 3 | [verb] been operating | 92 |
|
| 4 | [vb past] been operate | 33 |
|
| 5 | [vb past] [be] operating | 19 |
|
| 6 | [vb past] [been] operating | 19 |
|
| 7 | [vb past] be operating | 19 |
|
